C library function - atol()

Description

The C library function long int atol(const char *str) converts the string argument str to a long integer (type long int).

Declaration

Following is the declaration for atol() function.

long int atol(const char *str)

Parameters

• str -- This is the string containing the representation of an integral number.

Return Value

This function returns the converted integral number as a long int. If no valid conversion could be performed, it returns zero.

Example

The following example shows the usage of atol() function.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
   long val;
   char str[20];
   
   strcpy(str, "98993489");
   val = atol(str);
   printf("String value = %s, Long value = %ld\n", str, val);

   strcpy(str, "tutorialspoint.com");
   val = atol(str);
   printf("String value = %s, Long value = %ld\n", str, val);

   return(0);
}

Let us compile and run the above program, this will produce the following result:

String value = 98993489, Long value = 98993489
String value = tutorialspoint.com, Long value = 0