Printing calculator - Stephen Kochan exercise
This seems correct, and it works. Some simplifications are possible.

Don't repeat yourself

These lines appear many times in the code:


printf("= %.3f\n", output);
scanf("%f  %c", &amp;value, &amp;operator);



You can move this part after the switch block to reduce duplication.

Remove unnecessary elements

The exit variable is written to but never read.
It seems unused, so I suggest to remove it.

Coding style

It would be easier to read if you indent the body of case statements.

It's recommended to use braces with all if-else statements.

I suggest to put a space after #include and before &lt;stdio.h&gt;

Suggested implementation

Putting together the suggestions above, your implementation becomes simpler and easier to read:

#include &lt;stdio.h&gt;

int main(void)
{
    float value, output;
    char operator;

    printf("Please enter a value and operator to begin\n");
    scanf("%f %c", &amp;value, &amp;operator);

    while (operator != 'e' || operator != 'E')
    {
        switch(operator)
        {
            case 'S':
            case 's':
                output = value;
                break;

            case '+':
                output += value;
                break;

            case'-':
                output -= value;
                break;

            case '*':
                output *= value;
                break;

            case '/':
                if (value == 0)
                {
                    printf("Division by zero\n");
                }
                else
                {
                    output /= value;
                }
                break;

            case 'E':
            case 'e':
                output += value;
                printf("= %.3f\n", output);
                return 0;

            default:
                printf("Unidentified operator\n");
                return 0;
        }
        printf("= %.3f\n", output);
        scanf("%f %c", &amp;value, &amp;operator);
    }

    return 0;
}