Difference between revisions of "cpp/string/basic string/to string"
From cppreference.com
< cpp | string | basic string
m (A shorter equivalent re-formulation with "buf" intro.) |
m (accept → contain) |
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Converts a numeric value to {{lc|std::string}}. | Converts a numeric value to {{lc|std::string}}. | ||
| − | Let {{tti|buf}} be an internal to the conversion functions buffer, sufficiently large to | + | Let {{tti|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 {{c|std::sprintf(buf, "%d", value)}}. | @1@ Converts a signed integer to a string as if by {{c|std::sprintf(buf, "%d", value)}}. | ||
Revision as of 15:10, 2 June 2023
| Defined in header <string>
|
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| 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).
Contents |
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_stringmay 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::coutprints by default, see the example. -
std::to_stringrelies on the current locale for formatting purposes, and therefore concurrent calls tostd::to_stringfrom 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
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) |
