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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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Disc2.iso
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vc98
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crt
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src
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atof.c
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C/C++ Source or Header
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1998-06-17
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2KB
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62 lines
/***
*atof.c - convert char string to floating point number
*
* Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Converts a character string into a floating point number.
*
*******************************************************************************/
#include <stdlib.h>
#include <math.h>
#include <cruntime.h>
#include <fltintrn.h>
#include <string.h>
#include <ctype.h>
/***
*double atof(nptr) - convert 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:
* nptr - pointer to string to convert
*
*Exit:
* returns floating point value of character representation
*
*Exceptions:
*
*******************************************************************************/
double __cdecl atof(
REG1 const char *nptr
)
{
#ifdef _MT
struct _flt fltstruct; /* temporary structure */
#endif /* _MT */
/* scan past leading space/tab characters */
while ( isspace((int)(unsigned char)*nptr) )
nptr++;
/* let _fltin routine do the rest of the work */
#ifdef _MT
return( *(double *)&(_fltin2( &fltstruct, nptr, strlen(nptr), 0, 0 )->
dval) );
#else /* _MT */
return( *(double *)&(_fltin( nptr, strlen(nptr), 0, 0 )->dval) );
#endif /* _MT */
}