coffee/fast_float
1
0
Fork 0
mirror of https://github.com/fastfloat/fast_float.git synced 2025-12-07 01:06:48 +08:00
Code Issues Packages Projects Releases Wiki Activity

Update README.md

Browse Source 
Added examples of usage FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN macros and documented allow_leading_plus and skip_white_space options
This commit is contained in:
HedgehogInTheCPP 2025-03-09 02:40:28 +03:00 committed by GitHub
parent f496321570
commit ac22204bcc
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
1 changed files with 43 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
README.md
View File

@ -357,6 +357,49 @@ int main() {
}
```
You also can use not standard options:
```C++
#include "fast_float/fast_float.h"
#include <iostream>
int main() {
std::string input = " +456";
double result;
fast_float::parse_options options{chars_format::allow_leading_plus | chars_format::skip_white_space};
auto answer = fast_float::from_chars_advanced(input.data(), input.data() + input.size(), result, options);
if ((answer.ec != std::errc()) || ((result != 456))) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
return EXIT_SUCCESS;
}
```
For special case scenarious, like mathematical or other AST like parcer that already process minus sign
and only pasre in FastFloat positive numbers in fixed, scientific or hex format and do not have inf or nan
in input you can use macros FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN that significantly reduce
the code size and improve performance:
```C++
#define FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
#include "fast_float/fast_float.h"
#include <iostream>
int main() {
std::string input = "23.14069263277926900572";
double result;
fast_float::parse_options options{chars_format::allow_leading_plus | chars_format::skip_white_space};
auto answer = fast_float::from_chars_advanced(input.data(), input.data() + input.size(), result, options);
if ((answer.ec != std::errc()) || ((result != 23.14069263277927 /*properly rounded value */)))
{ std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
input = "-23.14069263277926900572";
if (answer.ec == std::errc()) { std::cerr << "parsing failure, should failed on any sign\n"; return EXIT_FAILURE; }
input = "inf";
if (answer.ec == std::errc()) { std::cerr << "parsing failure, should failed on infinity\n"; return EXIT_FAILURE; }
input = "nan";
if (answer.ec == std::errc()) { std::cerr << "parsing failure, should failed on nan in input\n"; return EXIT_FAILURE; }
return EXIT_SUCCESS;
}
```
## Users and Related Work
The fast_float library is part of: