Showing posts with label string. Show all posts
Showing posts with label string. Show all posts

Sunday, September 30, 2012

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

Thursday, March 25, 2010

Avoid using unsafe string functions




Avoid using unsafe string functions (UsageOfStringFunctions.rule)


Description

This rule detects code that uses unsafe string functions from C library.

Benefits:

Prevents the use of functions which may cause buffer overflows.

According to David A. Wheeler (see reference below), "C functions users must avoid using dangerous functions that do not check bounds unless they've ensured that the bounds will never get exceed.

Functions to avoid in most cases (or ensure protection) include the functions strcpy(), strcat(), sprintf() (with cousin vsprintf()), and gets().

These should be replaced with functions such as strncpy(), strncat(), snprintf(), fgets(), respectively."

Example:

#include
void main( void )
{
char* str1 = "testcase";
char* str2 = "testcase";
char* str3=0;

str3 = strcat( str1, str2 ); // Violation
}

Repair:

#include
void main( void )
{
char* str1 = "testcase";
char* str2 = "testcase";
char* str3=0;

str3 = strncat( str1, str2, 16 ); // OK
}

References:
http://www.dwheeler.com/secure-programs/Secure-Programs-HOWTO/dangers-c.html

Author
ParaSoft


Tags: Avoid, unsafe, string, function, unsafe string, C library, buffer overflows, dangerous functions, strncpy, strncat, snprintf, fgets


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