用C语言实现计算器功能

计算器的一般实现：

#include<stdio.h>
int add(int x, int y)
{
	return x + y;
}
int sub(int x, int y)
{
	return x - y;
}
int mul(int x, int y)
{
	return x * y;
}
int div(int x, int y)
{
	return x / y;
}
int main()
{
	int input = 1;
	int a, b, ret;

	do
	{
		printf("*****************************\n");
		printf("**1.add     2.sub ***********\n");
		printf("**3.mul     4.div ***********\n");
		printf("**0.exit          ***********\n");
		printf("*****************************\n");
		scanf("%d", &input);
		switch (input)
		{
		case 1:
			printf("请输入操作数：");
			scanf("%d %d", &a, &b);
			ret = add(a, b);
			printf("ret=%d\n", ret);
			break;
		case 2:
			printf("请输入操作数：");
			scanf("%d %d", &a, &b);
			ret = sub(a, b);
			printf("ret = %d\n", ret);
			break;
		case 3:
			printf("请输入操作数：");
			scanf("%d %d", &a, &b);
			ret = mul(a, b);
			printf("ret = %d\n", ret);
			break;
		case 4:
			printf("请输入操作数：");
			scanf("%d %d", &a, &b);
			ret = div(a, b);
			printf("ret = %d\n", ret);
			break;
		case 0:
			printf("退出游戏");
			break;
		default:
			printf("选择错误");
			break;
		}
	} while (input);
	
	return 0;
}

利用函数指针数组实现计算器功能：

#include<stdio.h>
int add(int x, int y)
{
	return x + y;
}
int sub(int x, int y)
{
	return x - y;
}
int mul(int x, int y)
{
	return x * y;
}
int div(int x, int y)
{
	return x / y;
}
int main()
{

		int input = 1;
		int a, b, ret;
		int(*p[5])(int a, int b) = { 0,add,sub,mul,div };
		do
		{
			printf("*****************************\n");
			printf("**1.add     2.sub ***********\n");
			printf("**3.mul     4.div ***********\n");
			printf("**0.exit          ***********\n");
			printf("*****************************\n");
			scanf("%d", &input);
			if (input >= 1 && input <= 4)
			{
				printf("请输入操作数：");
				scanf("%d %d", &a, &b);
				ret = (*p[input])(a, b);
				printf("ret = %d", ret);
				break;
			}
			else if (input == 0)
			{
				printf("退出游戏。");
				break;
			}
			else
			{
				printf("输入错误。");
				break;
			}
			}while (input);
	return 0;
}  

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