int charreplace(char * string, int find_character, int replace_character) { int i, length, found; length = strlen(string); found = 0; for (i = 0; i < length; i++) { if (string[i] == find_character) { string[i] = replace_character; found++; } } return found; } int main(int argc, char *argv[]) { char * query_string = "cmd=and%20then%20the%22cat%22"; int replacecount; printf("original string : %s\n", query_string); replacecount = charcount(query_string, '%'); printf("%d occurrences to replace\n", replacecount); replacecount = charreplace(query_string, '%', 'Z'); printf("%d occurrences replaced\n", replacecount); printf("replaced string : %s\n", query_string); //replace_hex_with_ascii(query_string); return 0; }