C/stdlib.h/atoll

    
//Declaration:  long long int atoll(const char *str); 

    
  

  #include <stdlib.h>
  #include <stdio.h>
  int main(void)
  {
    char num1[80], num2[80];
    printf("Enter first: ");
    gets(num1);
    printf("Enter second: ");
    gets(num2);
    printf("The sum is: %ld.", atoll(num1)+atoll(num2));
    return 0;
  }
         
/*
Enter first: 1
Enter second: 2
The sum is: 3.
*/