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.

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 std::bad_alloc from the std::string 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 locale for formatting purposes, and therefore concurrent calls to std::to_string from multiple threads may result in partial serialization of calls. C++17 provides std::to_chars as a higher-performance locale-independent alternative.

Example

Run this code

#include <iostream>
#include <string>
 
int main()
{
    for (const double f : {23.43, 1e-9, 1e40, 1e-40, 123456789.0})
        std::cout << "std::cout: " << f << '\n'
                  << "to_string: " << std::to_string(f) << "\n\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
 
std::cout: 1.23457e+08
to_string: 123456789.000000

Compiler support
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Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Technical specifications
Symbols index
External libraries

Null-terminated strings
Byte strings
Multibyte strings
Wide strings
Classes
basic_string
basic_string_view (C++17)
char_traits

to_wstring (C++11)	converts an integral or floating point value to `wstring` (function)
stoulstoull (C++11)(C++11)	converts a string to an unsigned integer (function)
stoistolstoll (C++11)(C++11)(C++11)	converts a string to a signed integer (function)
stofstodstold (C++11)(C++11)(C++11)	converts a string to a floating point value (function)
to_chars (C++17)	converts an integer or floating-point value to a character sequence (function)