wcstof, wcstod, wcstold
Defined in header <wchar.h>
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(since C99) | |
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(since C95) (until C99) | |
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(since C99) | |
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(since C99) |
Interprets a floating point value in a wide string pointed to by str
.
Function discards any whitespace characters (as determined by std::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
orE
followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent)
binary floating-point expression. It consists of the following parts:
- (optional) plus or minus sign
0x
or0X
- nonempty sequence of hexadecimal digits optionally containing a decimal-point character (as determined by the current C
locale
) (defines significand) - (optional)
p
orP
followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent)
infinity expression. It consists of the following parts:
- (optional) plus or minus sign
INF
orINFINITY
ignoring case
not-a-number expression. It consists of the following parts:
- (optional) plus or minus sign
NAN
orNAN(
char_sequence)
ignoring case of theNAN
part. char_sequence can only contain digits, Latin letters, and underscores. The result is a quiet NaN floating-point value.
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 NULL
, it is ignored.
Parameters
str | - | pointer to the null-terminated wide string to be interpreted |
str_end | - | pointer to a pointer to a wide character. |
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.
Example
#include <stdio.h>
#include <errno.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
References
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)
See also
(C99)(C99) |
converts a byte string to a floating point value (function) |
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