atof

#include <stdlib.h>

double atof (
  const unsigned char *string);   /* string to convert */

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

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.

atoi, atol

#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);
}