一個 switch 語句允許測試一個變數等於多個值時的情況。每個值稱為一個 case，且被測試的變數會對每個 switch case 進行檢查。

流程圖

//下面的語句是由使用者輸入的char變數值來控制
#include <stdio.h>
int main(void)
{
	char answer = 0;
	printf("Enter Y or N:");
	scanf(" %c",&answer);
	
	switch(answer)
	{
//可以把多個case值與一組語句聯絡起來
		case 'Y':case 'y':
			printf("You responded in the affirmative.\n");
			break;
		case 'N':case 'n':
			printf("You responded in the negative.\n");
			break;
		default:
			printf("You did not respond correctly...\n");
			break;
	}
	return 0;
}
 

 /*
 * switch語句中的case順序是可任意的，default不一定是最後一個case
 * */

//輸入1-10內的任意數字；各別數字對應對應不同的提示資訊，有些數字沒有。
#include <stdio.h>
int main()
{
	int choice = 0;
	printf("Pick a number between 1 and 10 and you may win a prize:");
	scanf("%d",&choice);

	if((choice > 10) || (choice < 1))
		choice = 11;
	
	switch(choice)
	{
		case 7:
			printf("You win the collected works of Amos of Amos Gruntfuttock.\n");
			break;
		case 2:
			printf("You win the folding thermomenter-pen-watch-unbrella.\n");
			break;
		case 8:
			printf("You win the lifetime supply of aspirin tablets.\n");
			break;
		case 11:
			printf("Try between 1 and 10.You wasted your guess.\n");
	
		default:
			printf("Sorry,you lose.\n");
			break;
	
	}
	return 0;
}
 

 執行結果顯示如下：

[[email protected] Test_20180418]# gcc switch.c 
[[email protected] Test_20180418]# ./a.out 
Pick a number between 1 and 10 and you may win a prize:3
Sorry,you lose.
[[email protected] Test_20180418]# ./a.out 
Pick a number between 1 and 10 and you may win a prize:7
You win the collected works of Amos of Amos Gruntfuttock.