Here's something which you might have to do as a big series of if/else or as a case statement, if it were not for function pointers.
Code:
#include <stdio.h>
#include <string.h>
#define ASIZE(x) (sizeof(x)/sizeof(x[0]))
/* a typedef to simplify the pointer to a function declaration */
typedef void (*fnptr)(char *);
/* associate a word with a function */
typedef struct {
char *keyword;
fnptr func;
} table_st;
/* the functions we want to call */
void do_file ( char *line ) {
printf( "do_file %s\n", line );
}
void do_edit ( char *line ) {
printf( "do_edit %s\n", line );
}
void do_print ( char *line ) {
printf( "do_print %s\n", line );
}
/* associate keywords with actions */
table_st table[] = {
{ "file", do_file },
{ "edit", do_edit },
{ "print", do_print },
};
/* search the table, and call the associated function */
void lookup_function ( char *keyword, char *param ) {
int i;
for ( i = 0 ; i < ASIZE(table) ; i++ ) {
if ( strcmp( table[i].keyword, keyword ) == 0 ) {
table[i].func( param );
}
}
}
int main ( ) {
lookup_function( "file", "foo.txt" );
lookup_function( "edit", "bar.txt" );
return 0;
}
My First Thread (functional pointers)
Okay, function pointers. Well I'll assume you know what they are but don't know when to use them. Just a quick example are callback functions. Callback functions are function pointers!! Also, you could have an array of function pointers for sin, cos and tan if you wanted and easily manipulate the pointer to call the functions. You'll see lots of function pointers in the Win32 API. Any specific questions?
thanks
