Source code of Windows XP (NT5)
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/***
*wtof.c - convert wchar_t string to floating point number
*
* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Converts a wide character string into a floating point number.
*
*Revision History:
* 05-18-00 GB written.
* 08-29-00 GB Fixed buffer overrun.
* 02-19-01 GB added _alloca and Check for return value of _malloc_crt
*
*******************************************************************************/
#ifndef _POSIX_
#ifndef _UNICODE
#define _UNICODE
#endif
#include <cruntime.h>
#include <internal.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <dbgint.h>
#include <errno.h>
#include <malloc.h>
/***
*double wtof(ptr) - convert wide char string to floating point number
*
*Purpose:
* atof recognizes an optional string of whitespace, then
* an optional sign, then a string of digits optionally
* containing a decimal point, then an optional e or E followed
* by an optionally signed integer, and converts all this to
* to a floating point number. The first unrecognized
* character ends the string.
*
*Entry:
* ptr - pointer to wide char string to convert
*
*Exit:
* returns floating point value of wide character representation
*
*Exceptions:
*
*******************************************************************************/
double __cdecl _wtof(
const wchar_t *ptr
)
{
char *cptr;
int malloc_flag = 0;
size_t len;
double retval;
while (iswspace(*ptr))
ptr++;
len = wcstombs(NULL, ptr, 0);
__try{
cptr = (char *)_alloca((len+1) * sizeof(wchar_t));
}
__except(1){ //EXCEPTION_EXECUTE_HANDLER
_resetstkoflw();
if ((cptr = (char *)_malloc_crt((len+1) * sizeof(wchar_t))) == NULL)
{
errno = ENOMEM;
return 0.0;
}
malloc_flag = 1;
}
// UNDONE: check for errors
// Add one to len so as to null terminate cptr.
wcstombs(cptr, ptr, len+1);
retval = atof(cptr);
if (malloc_flag)
_free_crt(cptr);
return retval;
}
#endif