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This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
Using Pointers to Functions
In Objective-C, function names are actually pointers. You can pass function names to other functions, and in the receiving function, you can call the passed function name if you treat it as a pointer.
For example, you can pass function names to this function, named caller_function(), and it will call the passed function:
void caller_function(void (*pointer_to_
function)(void))
{
(*pointer_to_function)();
}
To call a function pointer:
- Create a new program named functionpointers.m.
- In functionpointers.m, enter the code shown in Listing 4.19.
This code sets up a function named printem() and passes its name to caller_function().
- Add the code to implement caller_function(), which will call the function pointer you pass to it (Listing 4.20).
- Save functionpointers.m.
- Run the functionpointers.m program.
You should see the following:
Hello there
Listing 4.20. The functionpointers.m program.
#include <stdio.h>
void printem(void);
void caller_function(void (*pointer_to_
function)(void));
int main()
{
caller_function(printem);
return 0;
}
void printem(void)
{
printf("Hello there");
}
void caller_function(void (*pointer_to_
function)(void))
{
(*pointer_to_function)();
}
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