Wrong Calculator

/********************************************************
 * Name: Calculator (Version 0 -- prototype)        *
 *                          *
 * Purpose:                     *
 *  Act like a simple 4 function calculator.    *
 *                          *
 * Usage:                       *
 *  Run the program.                *
 *  Type in an operator (+ - * /) and a number. *
 *  The operaton will be performed on the current   *
 *  result and a new result displayed.      *
 *                          *
 * Note:                        *
 *  This is the first attempt at doing this program.*
 *  It only works for + and because of a bug, even  *
 *  that fails.                 *
 ********************************************************/
/*+*/
#include <stdio.h>
char  line[100];/* line of data from the input */
int   result;   /* the result of the calculations */
char  operator; /* operator the user specified */
int   value;    /* value specified after the operator */

int main()
{
    result = 0; /* initialize the result */

    /* Loop forever (or till we hit the break statement) */
    while (1) {
        printf("Result: %d\n", result);

        printf("Enter operator and number: ");
        fgets(line, sizeof(line), stdin);
        sscanf(line, "%c %d", &operator, &value);

        if (operator = '+') {
            result += value;
        } else {
            printf("Unknown operator %c\n", operator);
        }
    }
}