如何在 c 工作中使用函数指针？

#如何在 c 工作中使用函数指针？| 来源: 网络整理| 查看: 265

Function pointers in C

Let's start with a basic function which we will be pointing to:

int addInt(int n, int m) { return n+m; }

First thing, let's define a pointer to a function which receives 2 ints and returns an int:

int (*functionPtr)(int,int);

Now we can safely point to our function:

functionPtr = &addInt;

Now that we have a pointer to the function, let's use it:

int sum = (*functionPtr)(2, 3); // sum == 5

Passing the pointer to another function is basically the same:

int add2to3(int (*functionPtr)(int, int)) { return (*functionPtr)(2, 3); }

We can use function pointers in return values as well (try to keep up, it gets messy):

// this is a function called functionFactory which receives parameter n // and returns a pointer to another function which receives two ints // and it returns another int int (*functionFactory(int n))(int, int) { printf("Got parameter %d", n); int (*functionPtr)(int,int) = &addInt; return functionPtr; }

But it's much nicer to use a typedef:

typedef int (*myFuncDef)(int, int); // note that the typedef name is indeed myFuncDef myFuncDef functionFactory(int n) { printf("Got parameter %d", n); myFuncDef functionPtr = &addInt; return functionPtr; }

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