strtoimax, _strtoimax_l, wcstoimax, _wcstoimax_l

项目
06/05/2017

The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.

The latest version of this topic can be found at strtoimax, _strtoimax_l, wcstoimax, _wcstoimax_l.

Converts a string to an integer value of the largest supported signed integer type.

Syntax

intmax_t strtoimax(  
   const char *nptr,  
   char **endptr,  
   int base   
);  
intmax_t wcstoimax(  
   const wchar_t *nptr,  
   wchar_t **endptr,  
   int base   
);  
intmax_t _strtoimax_l(  
   const char *nptr,  
   char **endptr,  
   int base,  
   _locale_t locale  
);  
intmax_t _wcstoimax_l(  
   const wchar_t *nptr,  
   wchar_t **endptr,  
   int base,  
   _locale_t locale  
);

Parameters

nptr
Null-terminated string to convert.

endptr
Pointer to the character that stops the scan.

base
Number base to use.

locale
The locale to use.

Return Value

strtoimax returns the value that's represented in the string nptr, except when the representation would cause an overflow—in that case, it returns INTMAX_MAX or INTMAX_MIN, and errno is set to ERANGE. The function returns 0 if no conversion can be performed. wcstoimax returns values analogously to strtoimax.

INTMAX_MAX and INTMAX_MIN are defined in stdint.h.

If nptr is NULL or the base is nonzero and either less than 2 or greater than 36, errno is set to EINVAL.

For more information about return codes, see errno, _doserrno, _sys_errlist, and _sys_nerr.

Remarks

The strtoimax function converts nptr to an intmax_t. The wide-character version of strtoimax is wcstoimax; its nptr argument is a wide-character string. Otherwise, these functions behave identically. Both functions stop reading the string nptr at the first character they cannot recognize as part of a number. This may be the terminating null character, or it may be the first numeric character that's greater than or equal to base.

The locale's LC_NUMERIC category setting determines recognition of the radix character in nptr; for more information, see setlocale, _wsetlocale. The functions that don't have the _l suffix use the current locale; _strtoimax_l and _wcstoimax_l are identical to the corresponding functions that don't have the _l suffix except that they instead use the locale that's passed in. For more information, see Locale.

If endptr is not NULL, a pointer to the character that stopped the scan is stored at the location that's pointed to by endptr. If no conversion can be performed (no valid digits were found or an invalid base was specified), the value of nptr is stored at the location that's pointed to by endptr.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
`_tcstoimax`	`strtoimax`	`strtoimax`	`wcstoimax`
`_tcstoimax_l`	`strtoimax_l`	`_strtoimax_l`	`_wcstoimax_l`

strtoimax expects nptr to point to a string of the following form:

[whitespace] [{+ | –}] [0 [{ x | X }]] [digits | letters]

A whitespace may consist of space and tab characters, which are ignored; digits are one or more decimal digits; letters are one or more of the letters 'a' through 'z' (or 'A' through 'Z'). The first character that does not fit this form stops the scan. If base is between 2 and 36, then it is used as the base of the number. If base is 0, the initial characters of the string pointed to by nptr are used to determine the base. If the first character is '0' and the second character is not 'x' or 'X', the string is interpreted as an octal integer. If the first character is '0' and the second character is 'x' or 'X', the string is interpreted as a hexadecimal integer. If the first character is '1' through '9', the string is interpreted as a decimal integer. The letters 'a' through 'z' (or 'A' through 'Z') are assigned the values 10 through 35; only letters whose assigned values are less than base are permitted. The first character outside the range of the base stops the scan. For example, if base is 0 and the first character scanned is '0', an octal integer is assumed and an '8' or '9' character would stop the scan.

Requirements

Routine	Required header
`strtoimax`, `_strtoimax_l`, `wcstoimax`, `_wcstoimax_l`	<inttypes.h>

For additional compatibility information, see Compatibility.

通过