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 =