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std::string::front() in C++with Examples

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It is used to access the first character from the string. It returns a reference to the first character of the string. Unlike member string::begin, which returns an iterator to this same character, this function returns a direct reference.

Syntax:

string str ("GeeksforGeeks");

Accessing first character
char first_char = str.front();

Inserting character at start of string
str.front() = '#';

Parameter: This function takes no parameter 
Return value: A reference to the first character in the string 
Exception: If the string is empty it shows undefined behavior. 

The below examples illustrate the use of the above method: 

Program 1: 

CPP




// C++ program to demonstrate
// the use of the above method
 
#include <iostream>
 
// for std::string::front
#include <string>
 
using namespace std;
 
int main()
{
    string str("GeeksforGeeks");
 
    // Accessing first character of string
    char first_char = str.front();
 
    cout << "First character of string = "
         << first_char << endl;
 
    // Inserting a character at
    // the start of string
    str.front() = '#';
 
    cout << "New string = " << str << endl;
 
    return 0;
}


Output:

First character of string = G
New string = #eeksforGeeks

Program 2: It shows undefined behavior when the string is empty. 

CPP




// C++ program to demonstrate
// the use of the above method
 
#include <iostream>
 
// for std::string::front
#include <string>
 
using namespace std;
 
int main()
{
    string str(""); // Empty string
 
    // trying to access first character
    // of an empty string
    char first_char = str.front();
 
    cout << "First character of string = " << first_char
         << endl;
 
    // Inserting a character at
    // the start of an empty string
    str.front() = '#';
 
    cout << "New string = " << str << endl;
 
    return 0;
}


Output:

First character of string = 
New string =


Last Updated : 31 May, 2023
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