For every character in string

  1. Looping through the characters of a std::string, using a range-based for loop (it's from C++11, already supported in recent releases of GCC, clang, and the VC11 beta):

    std::string str = ???;
    for(char& c : str) {
        do_things_with(c);
    }
    
  2. Looping through the characters of a std::string with iterators:

    std::string str = ???;
    for(std::string::iterator it = str.begin(); it != str.end(); ++it) {
        do_things_with(*it);
    }
    
  3. Looping through the characters of a std::string with an old-fashioned for-loop:

    std::string str = ???;
    for(std::string::size_type i = 0; i < str.size(); ++i) {
        do_things_with(str[i]);
    }
    
  4. Looping through the characters of a null-terminated character array:

    char* str = ???;
    for(char* it = str; *it; ++it) {
        do_things_with(*it);
    }
    

A for loop can be implemented like this:

string str("HELLO");
for (int i = 0; i < str.size(); i++){
    cout << str[i];
}

This will print the string character by character. str[i] returns character at index i.

If it is a character array:

char str[6] = "hello";
for (int i = 0; str[i] != '\0'; i++){
    cout << str[i];
}

Basically above two are two type of strings supported by c++. The second is called c string and the first is called std string or(c++ string).I would suggest use c++ string,much Easy to handle.