atol

#include <stdlib.h>

long atol (
  char *string);   /* string to convert */

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

The string passed to atol must have the following format:

〚whitespace〛 〚{+|-}〛 digits

Where

The atol function returns the long integer value that is produced by interpreting the characters in string as a number.

If no conversion could be performed, 0 is returned.

atof, atoi

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

void tst_atol (void) {
  long l;
  char s [] = "8003488051";

  l = atol (s);
  printf ("ATOL(%s) = %ld\n", s, l);
}