std::string front() method

od C++20

// Non const version
constexpr CharT& front();

// Const version
constexpr const CharT& front() const;

od C++11

// Non const version
CharT& front();

// Const version
const CharT& front() const;

Returns a reference

to the first character in the string.

Undefined Behavior

Calling front() on an empty string is undefined behavior

.

Parameters

(none)

Return value

Reference to the first character.

Complexity

Constant - O(1).

Notes

For a string str, the expression str.front() is equivalent to *str.begin() and str[0].

Example

Main.cpp

#include <iostream>
#include <string>
 
int main()
{
  {
    std::string s("Exemplary");
    char& f = s.front();
    f = 'e';
    std::cout << s << '\n'; // "exemplary"
  }
 
  {
    std::string const c("Exemplary");
    char const& f = c.front();
    std::cout << &f << '\n'; // "Exemplary"
  }
}

Output

exemplary
Exemplary