wcstof, wcstod, wcstold - cppreference.com (original) (raw)
| Defined in header <wchar.h> | | | | ------------------------------------------------------------------------------------- | | ----------------------- | | float wcstof( const wchar_t* restrict str, wchar_t** restrict str_end ); | | (since C99) | | double wcstod( const wchar_t* str, wchar_t** str_end ); | | (since C95) (until C99) | | double wcstod( const wchar_t* restrict str, wchar_t** restrict str_end ); | | (since C99) | | long double wcstold( const wchar_t* restrict str, wchar_t** restrict str_end ); | | (since C99) |
Interprets a floating-point value in a wide string pointed to by str.
Function discards any whitespace characters (as determined by iswspace) until first non-whitespace character is found. Then it takes as many characters as possible to form a valid floating-point representation and converts them to a floating-point value. The valid floating-point value can be one of the following:
decimal floating-point expression. It consists of the following parts:
(optional) plus or minus sign
nonempty sequence of decimal digits optionally containing decimal-point character (as determined by the current C locale) (defines significand)
(optional)
**e**or**E**followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base 10)
| hexadecimal floating-point expression. It consists of the following parts: (optional) plus or minus sign 0x or 0X nonempty sequence of hexadecimal digits optionally containing a decimal-point character (as determined by the current C locale) (defines significand) (optional) p or P followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base 2) infinity expression. It consists of the following parts: (optional) plus or minus sign INF or INFINITY ignoring case not-a-number expression. It consists of the following parts: (optional) plus or minus sign NAN or NAN(char_sequence ) ignoring case of the NAN part. char_sequence can only contain digits, Latin letters, and underscores. The result is a quiet NaN floating-point value. | (since C99) |
|---|
- any other expression that may be accepted by the currently installed C locale.
The functions sets the pointer pointed to by str_end to point to the wide character past the last character interpreted. If str_end is a null pointer, it is ignored.
[edit] Parameters
| str | - | pointer to the null-terminated wide string to be interpreted |
|---|---|---|
| str_end | - | pointer to a pointer to a wide character. |
[edit] Return value
Floating-point value corresponding to the contents of str on success. If the converted value falls out of range of corresponding return type, range error occurs and HUGE_VAL, HUGE_VALF or HUGE_VALL is returned. If no conversion can be performed, 0 is returned.
[edit] Example
#include <errno.h> #include <stdio.h> #include <wchar.h> int main(void) { const wchar_t* p = L"111.11 -2.22 0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz"; printf("Parsing L"%ls":\n", p); wchar_t* end; for (double f = wcstod(p, &end); p != end; f = wcstod(p, &end)) { printf("'%.*ls' -> ", (int)(end-p), p); p = end; if (errno == ERANGE){ printf("range error, got "); errno = 0; } printf("%f\n", f); } }
Output:
Parsing L"111.11 -2.22 0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz": '111.11' -> 111.110000 ' -2.22' -> -2.220000 ' 0X1.BC70A3D70A3D7P+6' -> 111.110000 ' 1.18973e+4932' -> range error, got inf
[edit] References
C23 standard (ISO/IEC 9899:2024):
7.29.4.1.1 The wcstod, wcstof, and wcstold functions (p: TBD)
C17 standard (ISO/IEC 9899:2018):
7.29.4.1.1 The wcstod, wcstof, and wcstold functions (p: TBD)
C11 standard (ISO/IEC 9899:2011):
7.29.4.1.1 The wcstod, wcstof, and wcstold functions (p: 426-428)
C99 standard (ISO/IEC 9899:1999):
7.24.4.1.1 The wcstod, wcstof, and wcstold functions (p: 372-374)