std::basic_istream<CharT,Traits>:: operator>>

Extracts values from an input stream.

If extraction fails (e.g. if a letter was entered where a digit is expected), zero is written to value and failbit is set. For signed integers, if extraction results in the value too large or too small to fit in value , std:: numeric_limits < T > :: max ( ) or std:: numeric_limits < T > :: min ( ) (respectively) is written and failbit flag is set. For unsigned integers, if extraction results in the value too large or too small to fit in value , std:: numeric_limits < T > :: max ( ) is written and failbit flag is set.

Parameters

Return value

Notes

For overload ( 14 ) , when the extended floating-point type has a floating-point conversion rank that is not equal to the rank of any standard floating-point type, then double rounding during the conversion can result in inaccurate results. std::from_chars() can be used in situations where maximum accuracy is important.

Example

#include <iomanip>
#include <iostream>
#include <sstream>
 
int main()
{
    std::string input = "41 3.14 false hello world";
    std::istringstream stream(input);
 
    int n;
    double f;
    bool b;
 
    stream >> n >> f >> std::boolalpha >> b;
    std::cout << "n = " << n << '\n'
              << "f = " << f << '\n'
              << "b = " << std::boolalpha << b << '\n';
 
    // extract the rest using the streambuf overload
    stream >> std::cout.rdbuf();
    std::cout << '\n';
}

n = 41
f = 3.14
b = false
hello world

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also