分类: C/C++
2010-04-16 09:56:27
//这是一个求和函数的定义:
int add(int x, int y)
{
return(x + y);
}
//可以这样声明:
int add(int x, int y);
//也可以这样声明:
int add(int, int);
定义一个函数指针声明一个函数差不多, 用 (* ) 包括函数即可:
//像这样:
int (*pfun)(int, int);
//或这样:
int (*pfun)(int x, int y);
//也可以:
typedef int (*pfun)(int, int);
//这就声明了一个叫 pfun 的函数指针, 能被它指向的函数一定要有相同的参数格式.
1. 简单例子:
#include
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(void)
{
int (*pf)(int, int);
pf = add;
printf("%dn", pf(9, 3)); /* 12 */
pf = sub;
printf("%dn", pf(9, 3)); /* 6 */
pf = mul;
printf("%dn", pf(9, 3)); /* 27 */
pf = div;
printf("%dn", pf(9, 3)); /* 3 */
getchar();
return 0;
}
2. 函数指针数组:
#include
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(void)
{
int (*pf[4])(int, int) = {add, sub, mul, div};
printf("%dn", pf[0](9, 3)); /* 12 */
printf("%dn", pf[1](9, 3)); /* 6 */
printf("%dn", pf[2](9, 3)); /* 27 */
printf("%dn", pf[3](9, 3)); /* 3 */
getchar();
return 0;
}
3. 用函数指针做参数:
#include
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 math(int(*pfun)(int, int), int x, int y) {
return pfun(x, y);
}
int main(void)
{
printf("%dn", math(add, 9, 3)); /* 12 */
printf("%dn", math(sub, 9, 3)); /* 6 */
printf("%dn", math(mul, 9, 3)); /* 27 */
printf("%dn", math(div, 9, 3)); /* 3 */
getchar();
return 0;
}