How to validate user input?

In the program written below how i can ensure that only integer valu开发者_开发知识库e is entered? And if character is entered the program should convert it to its ASCII equivalent and then add them and show output as number. Please help me......

#include<stdio.h>
int main(int argc, char **argv)
{
 int a,b,c;
 printf("enter two numbers:-");
 scanf("%d \t %d",&a,&b);
 c=a+b;
 printf("addition of numbers= %d",c);
}

scanf returns the number of items that it successfully read, so you can check to make sure that it returns the same number that you expect. For example,

if (scanf("%d \t %d", &a, &b) != 2)
{
    // handle error
}

Note that \t is a whitespace character, and whitespace is ignored by scanf.

Just to add to what James said.

Dont forget to flush stdin

#include<stdio.h>
int main(int argc, char **argv)
{
 int a,b,c;

 printf("enter two numbers:-");
 if( scanf("%d \t %d",&a,&b)  == 2 )
 {
    c=a+b;
     printf("addition of numbers= %d",c);
 }
 else {
        printf("please enter a valid input");
        getchar(); // the getchar will clear the stdin otherwise next time you go do 
                   // a scanf it might not work. 
    }
}