From cppreference.com
Defined in header
std::stringto_string(intvalue); (1) (since C++11)std::stringto_string(longvalue); (2) (since C++11)std::stringto_string(longlongvalue); (3) (since C++11)std::stringto_string(unsignedvalue); (4) (since C++11)std::stringto_string(unsignedlongvalue); (5) (since C++11)std::stringto_string(unsignedlonglongvalue); (6) (since C++11)std::stringto_string(floatvalue); (7) (since C++11)std::stringto_string(doublevalue); (8) (since C++11)std::stringto_string(longdoublevalue); (9) (since C++11)Converts a numeric value to
.
Let buf be an internal to the conversion functions buffer, sufficiently large to contain the result of conversion.
1) Converts a signed integer to a string as if by std::sprintf(buf,"%d",value).
2) Converts a signed integer to a string as if by std::sprintf(buf,"%ld",value).
3) Converts a signed integer to a string as if by std::sprintf(buf,"%lld",value).
4) Converts an unsigned integer to a string as if by std::sprintf(buf,"%u",value).
5) Converts an unsigned integer to a string as if by std::sprintf(buf,"%lu",value).
6) Converts an unsigned integer to a string as if by std::sprintf(buf,"%llu",value).
7,8) Converts a floating point value to a string as if by std::sprintf(buf,"%f",value).
9) Converts a floating point value to a string as if by std::sprintf(buf,"%Lf",value).
(until C++26)1-9) Converts a numeric value to a string as if by std::format("{}",value).
(since C++26)Parameters
value - a numeric value to convert Return value
A string holding the converted value.
Exceptions
May throw
from the
constructor.
Notes
With floating point types std::to_string may yield unexpected results as the number of significant digits in the returned string can be zero, see the example.
The return value may differ significantly from what std::cout prints by default, see the example.
std::to_string relies on the current C locale for formatting purposes, and therefore concurrent calls to std::to_string from multiple threads may result in partial serialization of calls. The results of overloads for integer types do not rely on the current C locale, and thus implementations generally avoid access to the current C locale in these overloads for both correctness and performance. However, such avoidance is not guaranteed by the standard.
(until C++26)C++17 provides
as a higher-performance locale-independent alternative.
macroValueStdFeature
(C++26)Redefining std::to_string in terms of
Example
Run this code
#include<cstdio>#include<format>#include<initializer_list>#include<iostream>#include<string>#if __cpp_lib_to_string >= 202306Lconstexprautorevision(){return" (post C++26)";}#elseconstexprautorevision(){return" (pre C++26)";}#endifintmain(){for(constdoublef:{1.23456789555555,23.43,1e-9,1e40,1e-40,123456789.0}){std::cout<<"to_string:\t"<<std::to_string(f)<<revision()<<'\n';// Before C++26, the output of std::to_string matches std::printf.std::printf("printf:\t\t%f\n",f);// As of C++26, the output of std::to_string matches std::format.std::cout<<std::format("format:\t\t{}\n",f);std::cout<<"std::cout:\t"<<f<<"\n\n";}}Possible output:
to_string: 1.234568 (pre C++26) printf: 1.234568 format: 1.23456789555555 std::cout: 1.23457 to_string: 23.430000 (pre C++26) printf: 23.430000 format: 23.43 std::cout: 23.43 to_string: 0.000000 (pre C++26) printf: 0.000000 format: 1e-09 std::cout: 1e-09 to_string: 10000000000000000303786028427003666890752.000000 (pre C++26) printf: 10000000000000000303786028427003666890752.000000 format: 1e+40 std::cout: 1e+40 to_string: 0.000000 (pre C++26) printf: 0.000000 format: 1e-40 std::cout: 1e-40 to_string: 123456789.000000 (pre C++26) printf: 123456789.000000 format: 123456789 std::cout: 1.23457e+08 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)
(C++17)
converts an integer or floating-point value to a character sequence
(function)