C library function - atoi()

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Description

The C library function int atoi(const char *str) converts the string argument str to an integer (type int).

Declaration

Following is the declaration for atoi() function.

int atoi(const char *str)

Parameters

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

Return Value

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

Example

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

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

int main()
{
   int val;
   char str[20];
   
   strcpy(str, "98993489");
   val = atoi(str);
   printf("String value = %s, Int value = %d\n", str, val);

   strcpy(str, "tutorialspoint.com");
   val = atoi(str);
   printf("String value = %s, Int value = %d\n", str, val);

   return(0);
}

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

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

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