std::getline

Since C++11

Header: <string>

getline reads characters from an input stream and places them into a string:

# Declarations

template< class CharT, class Traits, class Allocator >
std::basic_istream<CharT, Traits>&
getline( std::basic_istream<CharT, Traits>& input,
std::basic_string<CharT, Traits, Allocator>& str, CharT delim );

template< class CharT, class Traits, class Allocator >
std::basic_istream<CharT, Traits>&
getline( std::basic_istream<CharT, Traits>&& input,
std::basic_string<CharT, Traits, Allocator>& str, CharT delim );

(since C++11)

template< class CharT, class Traits, class Allocator >
std::basic_istream<CharT, Traits>&
getline( std::basic_istream<CharT, Traits>& input,
std::basic_string<CharT, Traits, Allocator>& str );

template< class CharT, class Traits, class Allocator >
std::basic_istream<CharT, Traits>&
getline( std::basic_istream<CharT, Traits>&& input,
std::basic_string<CharT, Traits, Allocator>& str );

(since C++11)

# Parameters

input: the stream to get data from
str: the string to put the data into
delim: the delimiter character

# Return value

input

# Notes

When consuming whitespace-delimited input (e.g. int n; std::cin » n;) any whitespace that follows, including a newline character, will be left on the input stream. Then when switching to line-oriented input, the first line retrieved with getline will be just that whitespace. In the likely case that this is unwanted behaviour, possible solutions include:

# Example

#include <iostream>
#include <sstream>
#include <string>
 
int main()
{
    // greet the user
    std::string name;
    std::cout << "What is your name? ";
    std::getline(std::cin, name);
    std::cout << "Hello " << name << ", nice to meet you.\n";
 
    // read file line by line
    std::istringstream input;
    input.str("1\n2\n3\n4\n5\n6\n7\n");
    int sum = 0;
    for (std::string line; std::getline(input, line);)
        sum += std::stoi(line);
    std::cout << "\nThe sum is " << sum << ".\n\n";
 
    // use separator to read parts of the line
    std::istringstream input2;
    input2.str("a;b;c;d");
    for (std::string line; std::getline(input2, line, ';');)
        std::cout << line << '\n';
}

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
LWG 91	C++98	getline did not behave as an unformatted input function	behaves as an unformatted input function

# See also

getline