Creating my own calcutor but program doesnt work - c

Question

I decided to make a calcutor using code but my program just wont work.
When i enter my operand and new number it wont seem to scan the operand and number and it wont start the loop.
Thanks for the help.
#include <stdio.h>
#include <math.h>
float add(float x,float y);
float sub(float x,float y);
float div(float x,float y);
float exp(float x,float y);
float mult(float x,float y);
int main(){
float y,x;
char op;
printf("Type in a number\n");
scanf("%f",&x);
printf("Type in your operand and desired number\n");
scanf("%c",&op);
scanf("%f",&y);
while (!(op=='q')){
if(op=='+'){
printf("Your result is %.1f\n",add(x,y));
scanf("%c",&op);
scanf("%f",&y);
}
else if(op=='-'){
printf("Your result is %.1f\n",sub(x,y));
scanf("%c",&op);
scanf("%f",&y);
}
else if(op=='*'){
printf("Your result is %.1f\n",mult(x,y));
scanf("%c",&op);
scanf("%f",&y);
}
else if(op=='/'){
printf("Your result is %.1f\n",div(x,y));
scanf("%c",&op);
scanf("%f",&y);
}
else if(op=='^'){
printf("Your result is %.1f\n",exp(x,y));
scanf("%c",&op);
scanf("%f",&y);
}
}
printf("Your final result is %.1f\n",x);
return(0);
}
float add(float x,float y){
return (x+y);
}
float sub(float x,float y){
return (x-y);
}
float div(float x,float y){
return (x/y);
}
float exp(float x,float y){
x=pow(x,y);
return(x);
}
float mult(float x,float y){
return (x*y);
}

Answer 1

when you do
scanf("%c",&op);
you read first char that is in the input buffer. previous scanf left \n char in it, so you read that char.
What you want to do, is to get rid of all what's left behind scanf.
while(getchar()!='\n')
continue;
That will empty the buffer before you try to read.
Every use of scanf here will leave new line character in the buffer so to get rid of him, use above loop every time you try to read a character from input and you know that newline is there.

Answer 2

I think what's happening is that the newline character (the return/enter key) is left over in the input stream after the scanf("%f",&y); call and that's what being stored as the single character in the scanf("%c",&op); call.
So you'll need to discard the newline character at that point. Simplest way is to call scanf("%c",&op); twice when you need to read the single character. This should work on Mac and Unix. For Windows, you may need to read the character three times because Windows often considers the sequence "\r\n" as a newline sequence.
For portability, you can use a loop like this:
do {
op = getchar();
} while (op == '\n' || op == '\r');
And remove the scanf("%c",&op);. This loop replaces it.
Another option is to ask scanf itself to discard initial whitespace.
scanf(" %c",&op);
// ^ space
Also, see my answer to this very similar question.