ตัวอย่างการเขียนโปรแกรม โดยใช้ฟังก์ชั

1. 1: #include <stdio.h>
2: #include <stdlib.h>
3: #include <conio.h>
4:
5: void add() {
6: int num1, num2, result;
7:
8: printf("nn");
9: printf("Input number 1: ");
10: scanf("%d", &num1);
11: printf("Input number 2: ");
12: scanf("%d", &num2);
13:
14: result = num1 + num2;
15:
16: printf("t%d + %d = %dn", num1, num2, result);
17: }
18:
19: void subtrack() {
20: int num1, num2, result;
21:
22: printf("nn");
23: printf("Input number 1: ");
24: scanf("%d", &num1);
25: printf("Input number 2: ");
26: scanf("%d", &num2);
27:
28: result = num1 - num2;
29:
30: printf("t%d - %d = %dn", num1, num2, result);
31: }
32:
33: void multiple() {
34: int num1, num2, result;
35:
36: printf("nn");
37: printf("Input number 1: ");
38: scanf("%d", &num1);
39: printf("Input number 2: ");
40: scanf("%d", &num2);
41:
42: result = num1 * num2;
43:

2. 44: printf("t%d * %d = %dn", num1, num2, result);
45: }
46:
47: void divide() {
48: float num1, num2, result;
49:
50: printf("nn");
51: printf("Input number 1: ");
52: scanf("%f", &num1);
53: printf("Input number 2: ");
54: scanf("%f", &num2);
55:
56: result = num1 / num2;
57:
58: printf("t%.2f / %.2f = %.2fn", num1, num2, result);
59: }
60:
61: void menu() {
62: char c;
63:
64: do {
65: printf("n--- MAIN MENU ---n");
66: printf("A) Additionaln");
67: printf("S) Subtrackn");
68: printf("M) Multiplen");
69: printf("D) Dividen");
70: printf("Q) Quitn");
71: printf(" Select choice: ");
72: c = getch();
73:
74: switch (c) {
75: case 'a':
76: add();
77: break;
78: case 's':
79: subtrack();
80: break;
81: case 'm':
82: multiple();
83: break;
84: case 'd':
85: divide();
86: break;

3. 87: case 'q':
88: printf("nnGood bye!!!n");
89: }
90: } while ((c != 'q'));
91: }
92:
93: int main() {
94: menu();
95: system("PAUSE");
96: return 0;
97: }
98: