#include <stdio.h>
 
int main() {
    char op;
    double num1, num2, result;
 
    printf("=== Simple Calculator ===\n");
    printf("Enter an operator (+, -, *, /): ");
    scanf(" %c", &op);  // ช่องว่างก่อน %c เพื่อเคลียร์ buffer
 
    printf("Enter first number: ");
    scanf("%lf", &num1);
 
    printf("Enter second number: ");
    scanf("%lf", &num2);
 
    switch(op) {
        case '+':
            result = num1 + num2;
            printf("Result: %.2lf\n", result);
            break;
        case '-':
            result = num1 - num2;
            printf("Result: %.2lf\n", result);
            break;
        case '*':
            result = num1 * num2;
            printf("Result: %.2lf\n", result);
            break;
        case '/':
            if (num2 != 0)
                result = num1 / num2;
            else {
                printf("Error: Division by zero is not allowed.\n");
                return 1; // จบโปรแกรมพร้อมแจ้ง error
            }
            printf("Result: %.2lf\n", result);
            break;
        default:
            printf("Invalid operator!\n");
    }
 
    return 0;
}
 

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