//C/C++ samples //Replaces every char c with sub-string "XYZ" //Allocates memory for the new string on the heap - use delete [] if needed. char* swap_sub_str ( char* input_string, char c, char *sub_str ) { //do error checking here //count occurrences of the c character in the input string unsigned int count = 0; for (unsigned int i = 0; i < strlen(input_string); i++) { if (input_string[i] == c) count++; } if ( count == 0) return NULL; //nothing to do; //allocate new string unsigned int new_size = strlen(input_string) + count * strlen(sub_str); char * new_string = new char[new_size + 1]; //account for '/0' //construct the new string, replacing every occurrence of 'c' with substring char* k = new_string ; for (unsigned int i = 0; i < strlen(input_string); i++) { if (input_string[i] != c) { *k = input_string[i]; k++; } else { memcpy( k, sub_str, strlen(sub_str)); //don't include '/0' into memcopy k += strlen(sub_str); //move the pointer } } *k = '\0'; // add zero-terminator return new_string ; }