Simple Multichoice, Multivariable, Calculator Query - c

Question

I recently programmed this code (C) for a pretty simple calculator in Xcode.
It works mostly but does not display the answer for the sum/s.
The code is as follows:
#include <stdio.h>
int main()
{
//int's & chars-----------------
char SumMethod;
int firstnumber, secondnumber;
//int's & chars------------------
puts("Calculator v0.6");
printf("Please input first number: "); //Prompts 'firstnumber' input
scanf("%d", &firstnumber); //Scan's 'firstnumber' input and saves to '&firstnumber'
printf("Please input second number: "); //Prompts 'secondnumber' input
scanf("%d", &secondnumber); //Scan's 'secondnumber' input and saves to '&secondnumber
printf("d" "Please select Method: +(a), -(b), *(c), /(d): ");
scanf("%c", &SumMethod); //Scan's 'SumMethod' input
if(SumMethod=='a') {
printf ("%d",firstnumber + secondnumber); //This section detects the SumMethod and outputs the corrisponding sum
}
else if (SumMethod=='b'){
printf("%d",firstnumber-secondnumber);
}
else if (SumMethod=='c') {
printf("%d",firstnumber * secondnumber);
}
else if (SumMethod=='d') {
printf("%d",firstnumber / secondnumber);
}
}
For the solution i'm looking for a response that doesn't drastically change the code as how it is now is what I understand and because i'm relatively new to coding in general however if there is an obvious fix using useful common tools that would be much appreciated.
Thanks, Xenon

Answer 1

Your problem is that your comparisons are wrong. You need to compare your input to the LETTER a and not the (undefined and essentially random) values of the variables a,b,c,d.
so it is
if(SumMethod=='a')
instead of
if(SumMethod==a)
You don't need your variables a,b,c,d at all.