std::to_string
< cpp | string | basic 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
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 tostd::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() { double f = 23.43; double f2 = 1e-9; double f3 = 1e40; double f4 = 1e-40; double f5 = 123456789; 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::string f_str5 = std::to_string(f5); 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\n" << "std::cout: " << f5 << '\n' << "to_string: " << f_str5 << '\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
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) |