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C251 User's Guide

C251 Introduction Compiling Programs Language Extensions Preprocessor Advanced Programming Error Messages Library Reference Library Files Source Code Standard Types jmp_buf va_list Macros CBYTE CVAR CARRAY DARRAY DBYTE DVAR HARRAY HBYTE HVAR NARRAY NBYTE NVAR XARRAY XBYTE XVAR Routines by Category Buffer Manipulation Routines Character Routines Data Conversion Routines Intrinsic Routines Math Routines Memory Allocation Routines Stream I/O Routines String Routines Variable Length Argument Routines Miscellaneous Routines Include Files SFR Definitions absacc.h assert.h ctype.h float.h intrins.h limits.h math.h setjmp.h stdarg.h stddef.h stdio.h stdlib.h string.h Reference _chkdouble_ _chkfloat_ _crol_ _cror_ _getkey _irol_ _iror_ _lrol_ _lror_ _nop_ _testbit_ _tolower _toupper abs acos asin assert atan atan2 atof atoi atol cabs calloc ceil cos cosh exp fabs fcalloc ffree finit_mempool floor fmalloc fmemcpy fmemset frealloc free getchar gets hmemccpy hmemchr hmemcmp hmemcpy hmemmove hmemset hstrcmp hstrcpy hstrlen hstrncpy init_mempool isalnum isalpha iscntrl isdigit isgraph islower isprint ispunct isspace isupper isxdigit labs log log10 longjmp malloc memccpy memchr memcmp memcpy memmove memset modf offsetof pow printf putchar puts rand realloc scanf setjmp sin sinh sprintf sqrt srand sscanf strcat strchr strcmp strcpy strcspn strlen strncat strncmp strncpy strpbrk strpos strrchr strrpbrk strrpos strspn tan tanh toascii toint tolower toupper ungetchar va_arg va_end va_start vprintf vsprintf xcalloc xfree xinit_mempool xmalloc xmemcpy xmemset xrealloc Appendix

atof

Summary
#include <stdlib.h>

double atof (
  char *string);   /* string to convert */
Description

The atof function converts string into a floating-point value. The input string must be a sequence of characters that can be interpreted as a floating-point number. This function stops processing characters from string at the first one it cannot recognize as part of the number.

The string passed to atof must have the following format:

〚{+|-}〛 digits.digits 〚{e|E} 〚{+|-}〛 digits

Where

digits

May be one or more decimal digits (0-9).
Return Value

The atof function returns the floating-point value produced by interpreting the characters in string as a number.

If no conversion could be performed, NaN (not a number) is returned.

See Also

atoi, atol

Example
#include <stdlib.h>
#include <stdio.h> /* for printf */

void tst_atof (void) {
  float f;
  char s [] = "1.23";

  f = atof (s);
  printf ("ATOF(%s) = %f\n", s, f);
}

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