std::string examples

constructors 1.

#include 
#include 
using namespace std;

int main () 
{
    char *line = "short line for testing";
    
    // with no arguments
    string s1;
    s1 = "Anatoliy";
    cout << "s1  is: " << s1 << endl;

    // copy constructor
    string s2 (s1);
    cout << "s2  is: " << s2 << endl;

    // one argumen
    string s3 (line);
    cout << "s3  is: " << s3 << endl;

    // first argumen C string
    // second number of characters
    string s4 (line,10);
    cout << "s4  is: " << s4 << endl;

    // 1 - C++ string
    // 2 - start position
    // 3 - number of characters
    string s5 (s3,6,4); // copy word 'line' from s3
    cout << "s5  is: " << s5 << endl;

    // 1 - number characters
    // 2 - character itself
    string s6 (15,'*');
    cout << "s6  is: " << s6 << endl;

    // 1 - start iterator
    // 2 - end iterator
    string s7 (s3.begin(),s3.end()-5);
    cout << "s7  is: " << s7 << endl;

    // you can instantiate string with assignment
    string s8 = "Anatoliy";
    cout << "s8  is: " << s8 << endl;

    return 0;
}
OUTPUT:
// s1  is: Anatoliy
// s2  is: Anatoliy
// s3  is: short line for testing
// s4  is: short line
// s5  is: line
// s6  is: ***************
// s7  is: short line for te
// s8  is: Anatoliy


getline 1.


/* 1  getline ( intut_stream, str, delim );
  Extracts characters from intut_stream and stores them
  in str until s.max_size() characters have been extracted,
  the end of file occurs, or delim is encountered, in which
  case delim is extracted from istr but is not stored in s
  2 getline( Iter, str )
  Inputs a string value for str as in the preceding func­
  tion with delim =
*/
#include 
#include 
#include 
#include 
using namespace std;

int main () 
{
    string str;
    cout << "Enter string (EOL = $) : ";
    getline (cin, str, '$');
    cout << "Str is : " << str << endl;

    ifstream In("data.dat");
    vector v;

    cout << endl << "Read data from file" << endl;
    while ( ! In.eof() )
    {
     getline (In, str);
     v.push_back(str);
    }

    copy (v.begin(),v.end(),
      ostream_iterator(cout,"\n"));
    cout << endl;
     

    return 0;
}
OUTPUT:
// Enter string (EOL = $) : Str is : first line
// second line$
// 
// Read data from file
// file: "data.dat"
// second line
// last line


 << >> operators 1.

#include 
#include 
using namespace std;

int main () 
{
    string str;

    cout << "Enter string for testing : ";
    cin  >> str;
    cout << "\nString is : " << str << endl;

    cout << "Enter string for testing "
      << "(d to quit) : ";
    while ( cin >> str )
    {
     cout << endl;
     cout << "String is : " << str << endl;
     cout << "Enter string for testing "
             << "(d to quit) : ";
    }

    return 0;
}
OUTPUT:
// Enter string for testing : first
// String is : first
// Enter string for testing (d to quit) : second
// String is : second
// Enter string for testing (d to quit) : third
// String is : third
// Enter string for testing (d to quit) : 


 + += = operators 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "Hello";
    cout << "str is : " << str << endl;
    str += ",";
    str += ' ';
    cout << "str is : " << str << endl;

    string s;
    s = str + "World";
    cout << "s is : " << s << endl;

    char ch = '!';
    s += ch;
    cout << "s is : " << s << endl;

    return 0;
}
OUTPUT:
// str is : Hello
// str is : Hello, 
// s is : Hello, World
// s is : Hello, World!


append 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "Nobody is perfect";
    string s   = ""; // empty string
    char *ch   = "abcdef";

    // append string str at the end of s; 
    // return s
    
    // appends at the end of s a copy of the n characters
    // in str, starting at position pos; if n is too
    // large, characters are copied only until the end  
    // of str is reached;
    // returns s
    s.append(str,0,6);
    cout << "s is : " << s << endl;

    // appends copies of the characters in the range [inpIt1,
    // inpIt2] to s; returns s
    string::iterator inpIt1 = str.begin()+6;
                    //start from ' is'
    string::iterator inpIt2 = str.end();

    s.append(inpIt1,inpIt2);
    cout << "s is : " << s << endl;

    // appends three !
    s.append(3,'!');
    cout << "s is : " << s << endl;
    
    // appends the first n characters in ch at the end
    // of s; returns s
    s.append(ch,3);
    cout << "s is : " << s << endl;
    
    // appends charArray at the end of s; returns s
    s.append(ch,3);
    cout << "s is : " << s << endl;

    return 0;
}
OUTPUT:
// s is : Nobody
// s is : Nobody is perfect
// s is : Nobody is perfect!!!
// s is : Nobody is perfect!!!abc
// s is : Nobody is perfect!!!abcabc


assign 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "Nobody is perfect";
    string s   = "";
    char *ch   = "Robert Frost";

    // assigns a copy of str to s; returns s
    s.assign(str);
    cout << "s is : " << s << endl;

    
    // assigns to s a copy of the n characters in str, start­
    // ing at position 10: if n is too large, characters are
    // copied only until the end of str is reached: returns s
    s.assign(str,10,7); // perfect
    cout << "s is : " << s << endl;

    // assigns to s a string consisting of the first n charac­
    // ters in ch: returns s
    s.assign(ch,6);
    cout << "s is : " << s << endl;

    // assigns to s a copy of ch: returns s
    s.assign(ch);
    cout << "s is : " << s << endl;

    // assigns  to s a string consisting of the characters in
    // the range str.begin(), str.end(); returns s
    s.assign(str.begin(),str.end());
    cout << "s is : " << s << endl;

    // assigns to s a string consisting of n copies of ch;
    // returns s
    s.assign(17,'*');
    cout << "s is : " << s << endl;

    return 0;
}
OUTPUT:
// s is : Nobody is perfect
// s is : perfect
// s is : Robert
// s is : Robert Frost
// s is : Nobody is perfect
// s is : *****************


at 1.


// returns s[pos]
#include 
#include 
using namespace std;

int main () 
{
    string s = "Nobody is perfect";

    // Returns s[pos]
    for ( int pos = 0; pos < s.length(); ++pos )
     cout << s.at(pos) << " ";
    cout << endl;

    return 0;
}
OUTPUT:
// N o b o d y   i s   p e r f e c t 


begin 1.


// Returns an iterator positioned at the
// first character in a string
#include 
#include 
using namespace std;

int main () 
{
    string str = "C++ is best computer language";

    string::iterator It = str.begin();

    while ( It != str.end() )
    {
     if ( *It == ' ' )
      *It = '\n';
     cout << *It++;
    }
    cout << endl;
    
    return 0;
}
OUTPUT:
// C++
// is
// best
// computer
// language


c_str 1.


// returns (the base address of) a char 
// array containing the characters stored in s, 
// terminated by a null character.
#include 
#include 
using namespace std;

int main () 
{
    string str = "Anatoliy";
    char *ary = new char[str.length()+1];

    // strcpy ( ary, str ); that is wrong way
    strcpy ( ary, str.c_str() ); // that is correct

    cout << ary << endl;
    
    return 0;
}
OUTPUT:
// Anatoliy


capacity 1.


// returns the size (of type size_type)
// of the storage allocated in string
#include 
#include 
using namespace std;

int main () 
{
    string str = "C++ is best computer language";

    string::size_type cap;
    cap = str.capacity();

    cout << "Capacity of str is: " << cap << endl;
    cout << "Size of str is    : " << str.size() 
         << endl;
    cout << "Length of str is  : " << str.length() 
         << endl;

    cout << "Resize the str for 50 character" << endl;
    str.resize(50);
    cap = str.capacity();
    
    cout << "Capacity of str is: " << cap << endl;
    cout << "Size of str is    : " << str.size() 
         << endl;
    cout << "Length of str is  : " << str.length() 
         << endl;

    return 0;
}
OUTPUT:
// Capacity of str is: 32
// Size of str is    : 29
// Length of str is  : 29
// Resize the str for 50 character
// Capacity of str is: 64
// Size of str is    : 50
// Length of str is  : 50


compare 1.

#include 
#include 
using namespace std;

int main () 
{
    string str1 = "string";
    string str2 = "String";
    string str3 = "second string";
    char ch[]   = "first string";

    cout << "string str1 is : " << str1 << endl;
    cout << "string str2 is : " << str2 << endl;
    cout << "char ary ch is : " << ch   << endl;
    cout << "string str3 is : " << str3 << endl;
    cout << endl;

    // compare str1 and str2
    cout << "1." << endl;
    size_t comp = str1.compare(str2);
    cout << "String str1 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
         << "not equal";
    cout << " to string str2" << endl;

    // compare str1 and literal string "string"
    cout << "2." << endl;
    comp = str1.compare("string");
    cout << "String str1 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
        << "not equal";
    cout << " to array of char \"string\"" << endl;

    // 3. and 4. doesn't work with Microsoft 
    // Visual Studio compiler
 
    // compare str3 start from pos 7 to 5
    // with str1
    cout << "3." << endl;
    comp = str3.compare(str1,7,5);
    cout << "Part of string str3 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
        << "not equal";
    cout << " to str1" << endl;

    // compare str3 start from pos 7
    // with literal string "string"
    cout << "4." << endl;
    comp = str3.compare("string",7);
    cout << "Part of string str3 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
        << "not equal";
    cout << " to C string \"string\"" << endl;

    // next 4 'compare' functions
    // doesn't work with GNU compiler
 
    cout << "5." << endl;
    comp = str1.compare(6,10,ch);
    cout << "String str1 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
    << "not equal";
    cout << " to part of char ary \"first string\"" 
    << endl;

    cout << "6." << endl;
    comp = str1.compare(0,3,str3);
    cout << "Part of str1 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
    << "not equal";
    cout << " to string \"second string\"" 
    << endl;

    cout << "7." << endl;
    comp = str1.compare(1,3,str2,1,3);
    cout << "String str1 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
    << "not equal";
    cout << " to part of string \"second string\"" 
    << endl;

    cout << "8." << endl;
    comp = str1.compare(1,3,str2,1,3);
    cout << "String str1 is ";
    ( comp == 0 ) ? cout << "equal" : cout 
    << "not equal";
    cout << " to part of string \"second string\"" 
    << endl;

    return 0;
}
OUTPUT: GNU compiler
// string str1 is : string
// string str2 is : String
// char ary ch is : first string
// string str3 is : second string
// 
// 1.
// String str1 is not equal to string str2
// 2.
// String str1 is equal to array of char "string"
// 3.
// Part of string str3 is equal to str1
// 4.
// Part of string str3 is equal to C string "string"
// 5.
// 6.
// 7.
// 8.

OUTPUT: Microsoft Visual Studio compiler
// string str1 is : string
// string str2 is : String
// char ary ch is : first string
// string str3 is : second string
//
// 1.
// String str1 is not equal to string str2
// 2.
// String str1 is equal to array of char "string"
// 3.
// 4.
// 5.
// String str1 is not equal to part of char ary "first
// string"
// 6.
// Part of str1 is not equal to string "second string"
// 7.
// String str1 is equal to part of string "second string"
// 8.
// String str1 is equal to part of string "second string"
// Press any key to continue


copy 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "First Name: Robert";
    char fname[255];
    cout << "str is: " << str << endl;

    int n = str.find(':');

    str.copy(fname, // copy to array
            n+1,    // how many char
            0);     // start position from str
    
    // must terminate fname with '\0';
    fname[n+1] = 0;
    
    cout << "fname is: " << fname << endl;

    return 0;
}
OUTPUT:
// str is: First Name: Robert
// fname is: First Name:


empty 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "*******";

    while ( ! str.empty() )
    {
     cout << str << endl;
     str.erase(str.end()-1);
    }
    cout << endl;

    return 0;
}
OUTPUT:
// *******
// ******
// *****
// ****
// ***
// **
// *


end 1.


// returns an iterator porsitioned immediately
// after the last character in string
#include 
#include 
using namespace std;

int main () 
{
    string s;
    string str = "*************************";
    size_t pos = str.length();

    while ( pos )
    {
     s.assign ( str.begin(),str.end() - pos+1);
     cout << s << endl;
     pos -= 5;
    }

    return 0;
}
OUTPUT:
// *
// ******
// ***********
// ****************
// *********************


erase 1.

#include 
#include 
#include 
using namespace std;

int main () 
{
    string str, s;

    for ( char ch = 'a'; ch <= 'z'; ch++ )
        str.append(1,ch);
    s = str;
    cout << "str is: " << str << endl;
    cout << "s   is: " << str << endl;
    
    // removes 13 characters from the beginning
    str.erase(0,13);
    cout << "Erased range fron str : " << str << endl; 
    // removes 13 characters starts from 14
    str = s.erase(13,13);
    cout << "Erased range from s   : " << str << endl;

    // removes one character pointed by s.begin()
    cout << endl << "Erase one, second character from s"
         << endl;
    s.erase(s.begin()+1);
    cout << "s     is: " << s << endl;
    
    // removes range of characters
    s.erase(s.begin(),s.begin()+4);
    cout << "s     is: " << s << endl;

    return 0;
}
OUTPUT:
// str is: abcdefghijklmnopqrstuvwxyz
// s   is: abcdefghijklmnopqrstuvwxyz
// Erased range fron str : nopqrstuvwxyz
// Erased range from s   : abcdefghijklm
// 
// Erase one, second character from s
// s     is: acdefghijklm
// s     is: fghijklm


find 1.

#include 
#include 
#include 
using namespace std;

int main () 
{
    string  str("C++ is best language");
    int pos1, pos2; // size_t or size_type 
                    // work not correct
    // search for first string "best" inside of str
    // default position is 0
    pos1 = str.find ("best");
    cout << "Word best is found on position " << pos1+1 
         << endl;
    
    // if pattern is not found - return -1
    pos2 = str.find ("best",pos1+1);
    cout << "Word best is found on position " << pos2+1 
         << endl;

    // search for first occurrence of character
    pos1 = str.find('g');
    cout << "First character 'g' found on position " 
         << pos1
      << endl;

    // search for first occurrence of string
    string s = "is";
    pos1 = str.find (s);
    cout << "Word 'is' is found on position " << pos1+1 
         << endl;
    
    return 0;
}
OUTPUT:
// Word best is found on position 8
// Word best is found on position 0
// First character 'g' found on position 15
// Word 'is' is found on position 5


find_first_not_of 1.

#include 
#include 
using namespace std;

int main () 
{
    string  str("C++ is best language");
    cout << "str is: " << str << endl;

    int n = str.find_first_not_of("aeiouAEIOU");

    cout << "First consonant found at " << n+1
      << " position" << endl;
    
    return 0;
}
OUTPUT:
// str is: C++ is best language
// First consonant found at 1 position


find_first_not_of 2.

#include 
#include 
using namespace std;

int main () 
{
    string  str("C++ is best language");
    cout << "str is: " << str << endl;

    // search first not ' ',
    // start from position 7
    int n = str.find_first_not_of(' ',7);
    cout << "first not of space character "
      << "found at position " << n+1 << endl;
    
    return 0;
}
OUTPUT:
// str is: C++ is best language
// first not of space character found at position 8


find_first_not_of 3.

#include 
#include 
using namespace std;

int main () 
{
    string  str("C++ is best language");
    string  s = "C++";
    
    cout << "str is: " << str << endl;
    
    // search character from pattern 
    // using the first x chåracters in pattern.
    // the value position must be given
    int n = str.find_first_not_of("CBCD",0,3);
    cout << "first not 'C' is found at position "
      << n+1 << endl;
    
    // search first not of 
    // pattern is string
    n = str.find_first_not_of(s);
    cout << "first not of C++ is found "
      << "at position " << n+1 << endl;
    
    return 0;
}
OUTPUT:
// str is: C++ is best language
// first not 'C' is found at position 2
// first not of C++ is found at position 4


find_first_of 1.

#include 
#include 
using namespace std;

int main () 
{
    string  str("C++ is best language");
    string  s = "be";
    
    cout << "str is: " << str << endl;

    // search be start from position 2
    // if position is ommited - default is 0
    int n = str.find_first_of(s,2);
    cout << "first 'be' found at position "
      << n+1 << endl;

    // same as above but search for character
    n = str.find_first_of('l');
    cout << "first character 'l' found at "
      << "position " << n+1 << endl;

    // search 'first of' for the characters in
    // charary
    char charary[] = " bea";
    cout << "charary[] = \" bea\"" << endl;
    n = str.find_first_of(charary,0);
    cout << "first character from charary "
      << "found at position " << n+1 << endl;
    cout << "Note: position 4 is space" << endl;

    // same as above but third argumen is
    // number of character from which searching
    // starts
    // this variant of find_first_of dosn't
    // work properly with GNU compiler
    n = str.find_first_of(" bae",0,3);
    cout << "first character from charary "
      << "found at position " << n+1 << endl;

    return 0;
}
OUTPUT:
// str is: C++ is best language
// first 'be' found at position 8
// first character 'l' found at position 13
// charary[] = " bea"
// first character from charary found at position 4
// Note: position 4 is space
// first character from charary found at position 4


find_last_not_of 1.

#include 
#include 
using namespace std;

int main () 
{
    string  str("C++ is best language");
    string  s  = "langue";
    int pos = str.length()-1;
    cout << "str is: " << str << endl;
    
    // returns the highest position <= pos of a character
    // in str that does not match any charcter in s; 
    // returns nopos if there  is  no such position:
    // npos is the default value for pos
    int n =  str.find_last_not_of(s, pos);
    cout << "last_not_of 'langue' found at position "
      << n+1 << endl;

    // same as above but search for single character
    n = str.find_last_not_of('e');
    cout << "last_not_of 'e' found at position "
      << n+1 << endl;

    char ary[] = "be";
    // seawrch for occurence last_not_of
    // from pattern ary in str
    n = str.find_last_not_of(ary);
    cout << "last_not_of 'be' found at position "
      << n+1 << endl;
    
    return 0;
}
OUTPUT:
// str is: C++ is best language
// last_not_of 'langue' found at position 12
// last_not_of 'e' found at position 19
// last_not_of 'be' found at position 19


find_last_of 1.

#include 
#include 
using namespace std;

int main () 
{
    string  str("C++ is best language");
    string  s  = "g";
    cout << "str is: " << str << endl;
    cout << "s   is: " << s   << endl;

  int n = str.find_last_of(s);
  cout << "last_of '" << s << "' faund"
    << " at position " << n+1 << endl;

    n = str.find_last_of(' ');
    cout << "last_of ' ' faund"
      << " at position " << n+1 << endl;

    n = str.find_last_of(" la");
    cout << "last_of \" la\" faund"
      << " at position " << n+1 << endl;
    
    return 0;
}
OUTPUT:
// str is: C++ is best language
// s   is: g
// last_of 'g' faund at position 19
// last_of ' ' faund at position 12
// last_of " la" faund at position 18


insert 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "C++ language";
    string s   = "is best";
    char ch[]  = "C++ language";
    
    cout << "str is: " << str << endl;
    cout << "s   is: " << s   << endl;
    cout << "ch  is: " << s   << endl;
    
    // insert a copy of s into str
    // at position pos;
    string::size_type pos = 4;
    str.insert(pos,s);
    cout << "str is: " << str << endl;
    
    // insert a copy of ch into str at
    // the position specified by iterator
    // return an iterator positioned at
    // this copy
    int n = str.find('l');
    str.insert(str.begin() + n,' ');
    cout << "str is: " << str << endl;
    
    // like above but n x copies of char
    str.insert(str.end(),3,'!');
    cout << "str is: " << str << endl;
    
    // insert 4 char from ch into s
    // at the position 0
    s.insert(0,ch,4);
    cout << "s   is: " << s   << endl;
    
    // insert 8 characters from str
    // start from position n ('langu...')
    // into s at position x (end string)
    n = str.find('l');
    int x = s.length();
    s.insert(x,str,n,8);
    cout << "s   is: " << s   << endl;
    
    n = s.find('l');
    s.insert(s.begin()+n,' ');
    cout << "s   is: " << s   << endl;
    
    // insert range (begin - begin+7) of str 
    // into s at position begin+4
    s.insert(s.begin()+4,str.begin(),str.begin()+7);
    cout << "s   is: " << s   << endl;
    return 0;
}
OUTPUT:
// str is: C++ language
// s   is: is best
// ch  is: is best
// str is: C++ is bestlanguage
// str is: C++ is best language
// str is: C++ is best language!!!
// s   is: C++ is best
// s   is: C++ is bestlanguage
// s   is: C++ is best language
// s   is: C++ C++ is is best language


length 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "C++ is best computer language";
    cout << "str is: " << str << endl;
    
    cout << "Length of str is : "
         << str.length() << endl;
    
    return 0;
}
OUTPUT:
// str is: C++ is best computer language
// Length of str is : 29


max_size 1.


// returns a reverse iterator positioned
// at the last character in string
#include 
#include 
using namespace std;

int main () 
{
    string str = "C++ is best computer language";
    cout << "str is: " << str << endl;

    cout << "max_size of str is: "
         << str.max_size() << endl;

    return 0;
}
OUTPUT:
// str is: C++ is best computer language
// max_size of str is: 4294967294


rbegin 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "C++ is best computer language";
    cout << "str is: " << str << endl;

    // usual iterator doesn't work
    string::reverse_iterator It = str.rbegin();
    while ( It != str.rend() )
        cout << *It++;
    cout << endl;

    return 0;
}
OUTPUT:
// str is: C++ is best computer language
// egaugnal retupmoc tseb si ++C


replace 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "STL is created from Dennis Ritchie";
    string s1  = "was";
    string s2  = "developed";
    string s3  = "Stepanov alexander";
    cout << "str is: " << str << endl;

    cout << "replace 'is' for 'was'" << endl;
    str.replace(4, // start position in str
            2,     // how many characters
            s1);   // source for replasment
    
    cout << "str is: " << str << endl;
    
    cout <<"replace 'created' for 'developed'" << endl;
    int n = str.find('c'); // pos of 'created'
    int x = str.find("from") -1;

    str.replace(str.begin()+n,// start pointer
            str.begin()+x,    // end pointer
            s2);              // source
    
    cout << "str is: " << str << endl;

    cout << "replace 'Dennis' for 'alexander'" << endl;
    int x1 = str.find('D'); // search Dennis
    int x2 = str.find(' ',x1+1); // space after
    int y1 = s3.find("alex"); // search 'alex'
    int y2 = strlen("alexander");

    str.replace(x1, // start position in str
            x2-x1,  // how characters to replace
            s3,     // source for replacement
            y1,     // start positio from source
            y2);    // how chracter start from y1
    
    cout << "str is: " << str << endl;

    cout << "replace 'from' for 'by'" << endl;
    char ary[] = "bytes";
    n = str.find("from");

    // same variant possible with iterators
    // instead of number of position
    str.replace(n, // start position in str
            4,     // how many characters
            ary,   // source
            2);    // first 2 characters from source
    
    cout << "str is: " << str << endl;

    cout << "replace 'a' for 'A' (alexander)" << endl;
    n = str.find("alexander");

    str.replace(n,  // start position in str
            1,      // how character(s)
            1,      // how many copies of character
            'A');   // character for replasment
    cout << "str is: " << str << endl;

    cout << "replace 'Ritchie' for 'Stepanov'" << endl;
    x1 = str.find('R');
    y1 = s3.find(' ');

    str.replace(str.begin()+x1, // start pointer
            str.end(), // to the end of str
            s3.begin(), // start pointer from source
            s3.begin()+y1 // end pointer from
            );              // source
    cout << "str is: " << str << endl;

    return 0;
}
OUTPUT:
// str is: STL is created from Dennis Ritchie
// replace 'is' for 'was'
// str is: STL was created from Dennis Ritchie
// replace 'created' for 'developed'
// str is: STL was developed from Dennis Ritchie
// replace 'Dennis' for 'alexander'
// str is: STL was developed from alexander Ritchie
// replace 'from' for 'by'
// str is: STL was developed by alexander Ritchie
// replace 'a' for 'A' (alexander)
// str is: STL was developed by Alexander Ritchie
// replace 'Ritchie' for 'Stepanov'
// str is: STL was developed by Alexander Stepanov


reverse 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "Anatoliy Urbanskiy";
    cout << str.reverse() << endl;

    return 0;
}
OUTPUT:


resize 1.


// if  <=s.size(),  truncates rightmost 
// character in s to make it of size n; otherwise, adds
// copies of character ch to end of s to increase it size
// to n, or adds a default character value (usually a
// blank) if ch is omitted; return type is void
#include 
#include 
using namespace std;

int main () 
{
    string str = "Alexander Stepanov";
    cout << "str is: " << str << endl;
    cout << "size of str is: "
         << str.size() << endl;

    str.resize(11);

    cout << "after str.resize(11)" << endl;
    cout << "str is: " << str << endl;
    cout << "size of str is: "
         << str.size() << endl;

    str.resize(20,'.');

    cout << "after str.resize(20,'.')" << endl;
    cout << "str is: " << str << endl;
    cout << "size of str is: "
         << str.size() << endl;

    return 0;
}
OUTPUT:
// str is: Alexander Stepanov
// size of str is: 18
// after str.resize(11)
// str is: Alexander S
// size of str is: 11
// after str.resize(9,'.')
// str is: Alexander S.........
// size of str is: 20


rfind 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "We go step by step to the target";
    string s1  = "step";
    cout << "str is: " << str << endl;
    cout << "s1  is: " << s1  << endl;

    cout << "int n1 = str.find(s1)" << endl;
    int n1 = str.find(s1);
    cout << "n1 = " << n1+1 << endl;
    
    cout << "int n2 = str.rfind(s1)" << endl;
    int n2 = str.rfind(s1);
    cout << "n2 = " << n2+1 << endl;
    
    cout << "n3 = str.rfind(s1,n2-1)" << endl;
    int n3 = str.rfind(s1,n2-1);
    cout << "n3 = " << n3+1 << endl;

    cout << "n1 = str.rfind('t')" << endl;
    n1 = str.rfind('t');
    cout << "n1 = " << n1+1 << endl;
    
    cout << "n2 = str.rfind('t',n1-1)" << endl;
    n2 = str.rfind('t',n1-1);
    cout << "n2 = " << n2+1 << endl;
    
    char ch[] = "step";
    cout << "char ch[] = \"step\"" << endl;
    cout << "n1 = str.rfind(ch)" << endl;
    n1 = str.rfind(ch);
    cout << "n1 = " << n1+1 << endl;
    
    cout << "n2 = str.rfind(\"stabc\",10,2)" << endl;
    n2 = str.rfind("stabc", // pattern
            10,             // start position
            2);             // for first 2 char
                            // in pattern
    cout << "n2 = " << n2+1 << endl;
    
    return 0;
}
OUTPUT:
// str is: We go step by step to the target
// s1  is: step
// int n1 = str.find(s1)
// n1 = 7
// int n2 = str.rfind(s1)
// n2 = 15
// n3 = str.rfind(s1,n2-1)
// n3 = 7
// n1 = str.rfind('t')
// n1 = 32
// n2 = str.rfind('t',n1-1)
// n2 = 27
// char ch[] = "step"
// n1 = str.rfind(ch)
// n1 = 15
// n2 = str.rfind("stabc",10,2)
// n2 = 7


size 1.

#include 
#include 
using namespace std;

int main () 
{
    string str = "We go step by step to the target";
    string::size_type size = str.size();

    cout << "str is: " << str << endl;
    cout << "size of str = " << size << endl;
    
    return 0;
}
OUTPUT:
// str is: We go step by step to the target
// size of str = 32


substr 1.


// str.subsr(pos,n);
// returns a copy of the substring consisting
// of n characters from str, beginning at position pos
// (default value 0); if n is too large or is omitted,
// characters are copied only until the end of s is
// reached
#include 
#include 
using namespace std;

int main () 
{
    string str = "We go step by step to the target";
    cout << "str is: " << str << endl;

    int n = str.find("step");
    
    string s = str.substr(n);
    cout << "s   is: " << s << endl;

    s = str.substr(n,12);
    cout << "s   is: " << s << endl;
    
    return 0;
}
OUTPUT:
// str is: We go step by step to the target
// s   is: step by step to the target
// s   is: step by step


swap 1.

#include 
#include 
using namespace std;

int main () 
{
    string str1 = "Robert";
    string str2 = "Forest";
    cout << "str1 is: " << str1 << endl;
    cout << "str2 is: " << str2 << endl;
    cout << endl;

    cout << "str1.swap(str2)" << endl;
    cout << endl;

    str1.swap(str2);
    cout << "str1 is: " << str1 << endl;
    cout << "str2 is: " << str2 << endl;
    
    return 0;
}
OUTPUT:
// str1 is: Robert
// str2 is: Forest
// 
// str1.swap(str2)
// 
// str1 is: Forest
// str2 is: Robert

Ref:: http://anaturb.net/C/string_exapm.htm

CString vs std::string

cstring makes string.h accessable in namnespace std. cstring is located 
in /usr/include/c++ in my case. If you can't find it, just look for it 
by typing

locate cstring

It should be in a subdir of /usr/include


The file contains a comment, which might be useful:

/** @file cstring
* This is a Standard C++ Library file. You should @c #include this file
* in your programs, rather than any of the "*.h" implementation files.
*
* This is the C++ version of the Standard C Library header @c string.h,
* and its contents are (mostly) the same as that header, but are all
* contained in the namespace @c std.
*/

The Microsoft CString was written before the STL (and thus before std::string), but they are both designed to do basically the same thing.

The STL string has better out-of-the-box interoperability with STL algorithms.
The MS string has some really nice member functions.

Choose the one that suits your needs best.


Efficient in what sense?

the std::string will allow you to program more efficiently in terms of how you manage your time. Of course you can use it incorrectly and write really bad programs regardless of whether you define strings as char[] arrays or std::string objects. I just don't think that it is a fair question to be honest with you. Try defining some requirements. Write the program once with only c strings and once with std::string. Profile both programs and also keep track of how much time you spent writing each program. Look at the generated assembly code for each. There are a lot of factors to consider. Then report to us which is more efficient.



If you're using MFC, CString is a far better choice over std::string.
IMHO, CString is the only MFC class that is better then the STL version.

The std::string that comes with VC++ 6.0/7.x is very inefficient compare to CString.

std::string peforms very badly compare to CString.

Also IMHO, CString has a better string interface then std::string does.

CString is also easier to code when you want to be able to compile a project to either UNICODE or ANSI.

CString has an operator LPCTSTR(), so you don't have to explicitly cast.
With std::string, you have to use the c_str() member function to pass the pointer.
This point can also be consider a CON, but IMHO, the benifit far aways the down side.

CString has a GetBuffer() function which allows you to modify the buffer directly.
According to the C++ standard there's no portable way to modify the std::string buffer directly.

CString has a CompareNoCase function so you can make case insensitive comparisons.

CString works easier with many MFC and Windows API functions.

The major CON with CString is that is not portable. However, there are some CString versions on the net that are portable.


For more:
> > C headers exist in C++ in the form and the main difference is> that in the "no .h" form, all symbols (except macros) are declared in the> 'std' namespace. The .h form supposedly brings both std:: and regular> symbols. However, as admitted many times by library implementors, it is> rather difficult to follow those requirements. So, often the resulting> implementation is kind of in reverse: has all symbols in the> global namespace and has it in both global and 'std'. That's> my understanding of it, anyway.> 
Your understanding is correct. The safe rule is that if you want the 
names to be in the global namespace, use ; if you want them to 
be in std::, use .

Bash script: Stay Out Of Trouble

String Comparison Result 

string1 = string2                                            True if the strings are equal. 

string1 != string2                                          True if the strings are not equal. 

-n string                                                            True if the string is not null. 

-z string                                                            True if the string is null (an empty string).

Arithmetic Comparison Result 

expression1 -eq expression2 True if the expressions are equal. 

expression1 -ne expression2 True if the expressions are not equal. 

expression1 -gt expression2 True if expression1is greater than expression2. 

expression1 -ge expression2 True if expression1is greater than or equal to 

expression2. 

expression1 -lt expression2 True if expression1is less than expression2. 

expression1 -le expression2 True if expression1is less than or equal to 

expression2. 

! expression True if the expression is false, and vice versa.

File Conditional Result 

-d file True if the file is a directory. 

-e file True if the file exists. Note that, historically, the -e option has not 

been portable, so -f is usually used. 

-f file True if the file is a regular file. 

-g file True if set-group-id is set on file. 

-r file True if the file is readable. 

-s file True if the file has nonzero size. 

-u file True if set-user-id is set on file. 

-w file True if the file is writable. 

-x file True if the file is executable. 

Debugging Scripts 

Command Line Option setOption Description 

sh -n