std::to_string

Defined in header <string>
std::string to_string( int value );
(1) (since C++11)
std::string to_string( long value );
(2) (since C++11)
std::string to_string( long long value );
(3) (since C++11)
std::string to_string( unsigned value );
(4) (since C++11)
std::string to_string( unsigned long value );
(5) (since C++11)
std::string to_string( unsigned long long value );
(6) (since C++11)
std::string to_string( float value );
(7) (since C++11)
std::string to_string( double value );
(8) (since C++11)
std::string to_string( long double value );
(9) (since C++11)

Converts a numeric value to std::string.

1) Converts a signed decimal integer to a string with the same content as what std::sprintf(buf, "%d", value) would produce for sufficiently large buf.
2) Converts a signed decimal integer to a string with the same content as what std::sprintf(buf, "%ld", value) would produce for sufficiently large buf.
3) Converts a signed decimal integer to a string with the same content as what std::sprintf(buf, "%lld", value) would produce for sufficiently large buf.
4) Converts an unsigned decimal integer to a string with the same content as what std::sprintf(buf, "%u", value) would produce for sufficiently large buf.
5) Converts an unsigned decimal integer to a string with the same content as what std::sprintf(buf, "%lu", value) would produce for sufficiently large buf.
6) Converts an unsigned decimal integer to a string with the same content as what std::sprintf(buf, "%llu", value) would produce for sufficiently large buf.
7,8) Converts a floating point value to a string with the same content as what std::sprintf(buf, "%f", value) would produce for sufficiently large buf.
9) Converts a floating point value to a string with the same content as what std::sprintf(buf, "%Lf", value) would produce for sufficiently large buf.

Parameters

value - a numeric value to convert

Return value

a string holding the converted value.

Notes

std::to_string may yield unexpected results when used with floating point types and the return values may be substantially different from what std::cout would print, see the example.

Example

#include <iostream>
#include <string>
 
int main() 
{
    double f = 23.43;
    double f2 = 1e-9;
    double f3 = 1e40;
    double f4 = 1e-40;
    std::string f_str = std::to_string(f);
    std::string f_str2 = std::to_string(f2); // Note: returns "0.000000"
    std::string f_str3 = std::to_string(f3); // Note: Does not return "1e+40".
    std::string f_str4 = std::to_string(f4); // Note: returns "0.000000"
    std::cout << "std::cout: " << f << '\n'
              << "to_string: " << f_str  << '\n' << '\n'
              << "std::cout: " << f2 << '\n'
              << "to_string: " << f_str2 << '\n' << '\n'
              << "std::cout: " << f3 << '\n'
              << "to_string: " << f_str3 << '\n' << '\n'
              << "std::cout: " << f4 << '\n'
              << "to_string: " << f_str4 << '\n';
}

Output:

std::cout: 23.43
to_string: 23.430000
 
std::cout: 1e-09
to_string: 0.000000
 
std::cout: 1e+40
to_string: 10000000000000000303786028427003666890752.000000
 
std::cout: 1e-40
to_string: 0.000000

See also

(C++11)
converts an integral or floating point value to wstring
(function)
(C++11)(C++11)
converts a string to an unsigned integer
(function)
(C++11)(C++11)(C++11)
converts a string to a signed integer
(function)
(C++11)(C++11)(C++11)
converts a string to a floating point value
(function)
doc_CPP
2016-10-11 10:07:31
Comments
Leave a Comment

Please login to continue.