C语言写一个计算器的三种方法
-
方法一：常规方法
#include
int Add(int a, int b)
{
return a + b;
}
int Sub(int a, int b)
{
return a - b;
}
int Mul(int a, int b)
{
return a * b;
}
int Div(int a, int b)
{
return a / b;
}
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 = 1;
int x = 0;
int y = 0;
int ret = 0;
while (input)
{
menu();
printf("请选择：");
scanf_s("%d", &input);
if (input >= 1 && input <= 4)
{
printf("输入两个数：");
scanf_s("%d%d", &x, &y);
}
switch (input)
{
case 1:
ret = Add(x, y);
break;
case 2:
ret = Sub(x, y);
break;
case 3:
ret = Mul(x, y);
break;
case 4:
ret = Div(x, y);
break;
case 0:
printf("退出\n");
break;
default:
printf("输入错误\n");
break;
}
printf("ret = %d\n", ret);
}
return 0;
}
方法二：函数指针数组法
#include
int Add(int a, int b)
{
return a + b;
}
int Sub(int a, int b)
{
return a - b;
}
int Mul(int a, int b)
{
return a * b;
}
int Div(int a, int b)
{
return a / b;
}
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 = 1;
int x = 0;
int y = 0;
int ret = 0;
int(*p[5])(int, int) = { 0, Add, Sub, Mul, Div }; //有五个元素是为了方便标号对齐
while (input)
{
menu();
printf("请选择：");
scanf_s("%d", &input);
if (input >= 1 && input <= 4)
{
printf("输入两个数：");
scanf_s("%d%d", &x, &y);
ret = p[input](x, y);
printf("ret = %d\n", ret);
}
}
return 0;
}
方法三：回调函数法
#include
int Add(int a, int b)
{
return a + b;
}
int Sub(int a, int b)
{
return a - b;
}
int Mul(int a, int b)
{
return a * b;
}
int Div(int a, int b)
{
return a / b;
}
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 (*pfun) (int, int))
{
int x = 0;
int y = 0;
int ret = 0;
printf("输入两个数：");
scanf_s("%d%d", &x, &y);
ret = pfun(x, y);
printf("ret = %d\n", ret);
}
int main()
{
int input = 1;
int(*p[5])(int, int) = { 0, Add, Sub, Mul, Div };
while (input)
{
menu();
printf("请选择：");
scanf_s("%d", &input);
if (input >= 1 && input <= 4)
{
calc(p[input]); //传输的是加减乘除函数的地址
}
}
return 0;
}