Hello CodeForces
Here is some common string operations.

______**Accessing character**______
front -> Access the first first character
    Example: char ch = string_name.front();
back -> Access the last character
    Example: char ch = string_name.back();
at -> Access the specified character
    Example: char ch = string_name.at(position); //Here position maybe 0 to length-1

_____**Operations**_____
clear -> Clears the content
    Example: string_name.clear();  
push_back -> Appends a character to the end 
    Example: string_name.push_back('C'); // Here 'C' appends
pop_back ->  Removes the last character 
    Example: string_name.pop_back();

_____**Special**_____
string str(x, ch);
    str is any stiring variable.
    x is any integer value.
    ch is any character.
    the expressions means 'str' store x time(s) ch.
  Example: 
      string str(3, 'z'); // now str = "zzz". Try it

_____**Iteration**_____
begin -> Returns an iterator to the beginning
end -> Returns an iterator to the end 
rbegin -> Returns a reverse iterator to the beginning
rend -> Returns a reverse iterator to the end 
Using these itarator we can sort or reverse an string
  Example: 
    To sort elements in ascending order
      sort(string_name.begin(), string_name.end());
    To sort elements in descending order
      sort(string_name.rbegin(), string_name.rend());
    To reverse string
      reverse(string_name.begin(), string_name.end());

All of the syntax are written in C++ language. 
Discussions welcome in the comment section.
For more information or reference, visit: https://en.cppreference.com/w/cpp/string/basic_string