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| -rw-r--r-- | c.html.markdown | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/c.html.markdown b/c.html.markdown index 69bf099e..fba587fc 100644 --- a/c.html.markdown +++ b/c.html.markdown @@ -323,6 +323,30 @@ str_reverse(c); printf("%s\n", c); // => ".tset a si sihT" */ +/* +Functions are located in known memory addresses, so they can be called +through function pointers. Syntax may be initially confusing. + +Example: use str_reverse from a pointer +*/ +void str_reverse_through_pointer(char * str_in) { + // Define a function pointer variable, named f. + void (*f)(char *); // Signature should exactly match the target function. + f = &str_reverse; // Assign the address for the actual function (determined at runtime) + (*f)(str_in); // Just calling the function through the pointer + // f(str_in); // That's an alternate but equally valid syntax for calling it. +} + +/* +As long as function signatures match, you can assign any function to the same pointer. +Useful for passing handlers (or callback functions) around. +Function pointers are usually typedef'd for simplicity and readability, as follows: + +typedef void (*my_fnp_type)(char *); +... +my_fnp_type f; +*/ + /////////////////////////////////////// // User-defined types and structs /////////////////////////////////////// |