why this 3rd case in following program not execute properly?

Question

#include <stdio.h>

int main(void) {

int no1,no2,result;

float No1,No2,Result;

char a,b,c;

int choice;

printf("\n.............Menu...........");

printf("\n1.Addition of integers\n2.Addition of floats\n3.Addtion of characters");

printf("\nEnter your choice....");

scanf("%d",&choice);

switch(choice)

{

    case 1:

    printf("\nEnter the nos=");

    scanf("%d %d",&no1,&no2);

    result=a+b;

    printf("\nResult=%d",result);

    break;

    

    case 2:

    printf("\nEnter the nos=");

    scanf("%f %f",&No1,&No2);

    Result=No1+No2;

    printf("\nResult=%f",Result);

    break;

    

    case 3:

    printf("\nEnter the characters=");

    scanf("%c %c",&a,&b);

    c=a+b;

    printf("\nResult=%c",c);

    break;

    

    default:

    printf("\nYou Entered wrong choice.....");

    break;

    

}

return 0;

}

Answer 1

because character are not add

Comments

No,Addtion characters is possible.following program runs

void main()
{
char a,b,c;
printf("\nEnter the characters=");
scanf("%c %c",&a,&b);
c=a+b;
printf("\nRsult=%c",c);
}

Answer 2

addition characters is not the reason for reading the input  every time your clearing the buffer by using fpurge function present in stdlib.h.

scanf("%d",&choice);
__fpurge(stdin);
switch(choice)

Comments

Yes, I implement fflush function & it works. Thanks for your suggestions.

Answer 3

Case 3 is wrong, addition of char isnt possible directly, you can add then by adding their ascii values