_atodbl, _atodbl_l, _atoldbl, _atoldbl_l, _atoflt _atoflt_l
Visual Studio 2012
Converts a string to a double (_atodbl), long double (_atoldbl), or float (_atoflt).
int _atodbl( _CRT_DOUBLE * value, char * str ); int _atodbl_l ( _CRT_DOUBLE * value, char * str, locale_t locale ); int _atoldbl( _LDOUBLE * value, char * str ); int _atoldbl_l ( _LDOUBLE * value, char * str, locale_t locale ); int _atoflt( _CRT_FLOAT * value, char * str ); int _atoflt_l( _CRT_FLOAT * value, char * str, locale_t locale );
These functions convert a string to a floating-point value. The difference between these functions and the atof family of functions is that these functions do not generate floating-point code and hence do not result in hardware exceptions. Instead, error conditions are reported as an error code.
If a string does not have a valid interpretation as a floating-point value, value is set to zero and the return value is zero.
The versions of these functions with the _l suffix are identical except that they use the locale parameter passed in instead of the current thread locale.
// crt_atodbl.c
// Uses _atodbl to convert a string to a double precision
// floating point value.
#include <stdlib.h>
#include <stdio.h>
int main()
{
char str1[256] = "3.141592654";
char abc[256] = "abc";
char oflow[256] = "1.0E+5000";
_CRT_DOUBLE dblval;
_CRT_FLOAT fltval;
int retval;
retval = _atodbl(&dblval, str1);
printf("Double value: %lf\n", dblval.x);
printf("Return value: %d\n\n", retval);
retval = _atoflt(&fltval, str1);
printf("Float value: %f\n", fltval.f);
printf("Return value: %d\n\n", retval);
// A non-floating point value: returns 0.
retval = _atoflt(&fltval, abc);
printf("Float value: %f\n", fltval.f);
printf("Return value: %d\n\n", retval);
// Overflow.
retval = _atoflt(&fltval, oflow);
printf("Float value: %f\n", fltval.f);
printf("Return value: %d\n\n", retval);
return 0;
}
Double value: 3.141593 Return value: 0 Float value: 3.141593 Return value: 0 Float value: 0.000000 Return value: 0 Float value: 1.#INF00 Return value: 3
