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
);
Parameters
value
The double, long double, or float value produced by converting the string to a floating-point value. These values are wrapped in a structure.str
The string to be parsed to convert into a floating-point value.locale
The locale to use.
Return Value
Returns 0 if successful; possible error codes are _UNDERFLOW or _OVERFLOW, defined in the header file Math.h.
Remarks
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.
Requirements
Routines |
Required header |
|---|---|
_atodbl, _atoldbl, _atoflt _atodbl_l, _atoldbl_l, _atoflt_l |
<stdlib.h> |
Example
// 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