C语言代码（指针）test_2_29

C语言代码（指针）test_2_29

#define _CRT_SECURE_NO_WARNINGS 1


函数指针 - 指向函数的指针
函数指针变量 - 存放函数地址的变量
#include <stdio.h>

int Add(int x, int y)
{
	return x + y;
}

int main()
{
	printf("%p\n", Add);
	printf("%p\n", &Add);

	int (*pf)(int, int) = Add;//pf就是函数指针变量
	int ret = (*pf)(3, 4);
	int ret = pf(3, 4);
	int ret = *pf(3, 4);//err
	Add(3, 4);
	printf("%d\n", ret);

	return 0;
}



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 (*pf1)(int, int) = Add;
	int (*pf2)(int, int) = Sub;
	int (*pf3)(int, int) = Mul;
	int (*pf4)(int, int) = Div;

	int (* pfArr[4])(int, int) = {Add, Sub, Mul, Div};//pfArr就是函数指针数组
	int i = 0;
	for (i = 0; i < 4; i++)
	{
		int ret = pfArr[i](8, 4);
		printf("%d\n", ret);
	}

	return 0;
}




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;
}

想写一个计算机器：
完成2个整数的运行
1. 加法
2. 减法
3. 乘法
4. 除法


void menu()
{
	printf("*****************************************\n");
	printf("********  1. Add     2. Sub       *******\n");
	printf("********  3. Mul     4. Div       *******\n");
	printf("********  0. exit                 *******\n");
	printf("*****************************************\n");
}

int main()
{
	int input = 0;
	int x = 0;
	int y = 0;
	int ret = 0;
	do
	{
		menu();
		printf("请选择:");
		scanf("%d", &input);
		switch (input)
		{
		case 1:
			printf("请输入2个操作数:");
			scanf("%d %d", &x, &y);
			ret = Add(x, y);
			printf("%d\n", ret);
			break;
		case 2:
			printf("请输入2个操作数:");
			scanf("%d %d", &x, &y);
			ret = Sub(x, y);
			printf("%d\n", ret);
			break;
		case 3:
			printf("请输入2个操作数:");
			scanf("%d %d", &x, &y);
			ret = Mul(x, y);
			printf("%d\n", ret);
			break;
		case 4:
			printf("请输入2个操作数:");
			scanf("%d %d", &x, &y);
			ret = Div(x, y);
			printf("%d\n", ret);
			break;
		case 0:
			printf("退出计算器\n");
			break;
		default:
			printf("选择错误，重新选择\n");
			break;
		}
	} while (input);

	return 0;
}




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;
}

想写一个计算机器：
完成2个整数的运行
1. 加法
2. 减法
3. 乘法
4. 除法


void menu()
{
	printf("*****************************************\n");
	printf("********  1. Add     2. Sub       *******\n");
	printf("********  3. Mul     4. Div       *******\n");
	printf("********  0. exit                 *******\n");
	printf("*****************************************\n");
}

int main()
{
	int input = 0;
	int x = 0;
	int y = 0;
	int ret = 0;
	 创建一个函数指针的数组
	转移表
	int (*pfArr[5])(int, int) = {NULL,Add, Sub, Mul, Div};
	                           0    1    2    3    4
	do
	{
		menu();
		printf("请选择:");
		scanf("%d", &input);//2
		if (input >= 1 && input <= 4)
		{
			printf("请输入2个操作数:");
			scanf("%d %d", &x, &y);
			ret = pfArr[input](x, y);
			printf("%d\n", ret);
		}
		else if (input == 0)
		{
			printf("退出计算器\n");
			break;
		}
		else
		{
			printf("选择错误，重新选择\n");
		}
	} while (input);

	return 0;
}



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;
}

想写一个计算机器：
完成2个整数的运行
1. 加法
2. 减法
3. 乘法
4. 除法


void menu()
{
	printf("*****************************************\n");
	printf("********  1. Add     2. Sub       *******\n");
	printf("********  3. Mul     4. Div       *******\n");
	printf("********  0. exit                 *******\n");
	printf("*****************************************\n");
}

void Calc(int (*pf)(int, int))
{
	int x = 0;
	int y = 0;
	int ret = 0;
	printf("请输入2个操作数:");
	scanf("%d %d", &x, &y);
	ret = pf(x, y);
	printf("%d\n", ret);
}

int main()
{
	int input = 0;
	
	do
	{
		menu();
		printf("请选择:");
		scanf("%d", &input);
		switch (input)
		{
		case 1:
			Calc(Add);
			break;
		case 2:
			Calc(Sub);
			break;
		case 3:
			Calc(Mul);
			break;
		case 4:
			Calc(Div);
			break;
		case 0:
			printf("退出计算器\n");
			break;
		default:
			printf("选择错误，重新选择\n");
			break;
		}
	} while (input);

	return 0;
}