Problem with pointers in C

Martyr

/* I've just started to learn C, and I can't get the following code to compile
for me.
Its a problem with pointers.
I want to assign a function to a pointer from input by the user.
Dev-C++ Compiler says: ANSI C++ forbids implicit conversion from `void *' in assignment

It may be a little lame to you C coders here, but i require your help :)
What am i doing wrong here? */

#include <stdio.h>
#include <string.h>

#define NUMBER_OF_FUNCTIONS 3

void one(void);
void two(void);
void three(void);

void (*lpFunc)(void);

void usage(char *szModuleName);

char *szFunctions[NUMBER_OF_FUNCTIONS] = { "one","two", "three" };
void *lpFunctions[NUMBER_OF_FUNCTIONS] = { one, two, three };

int main(int argc, char *argv[])
{
 int function_count;

 if (argc != 2)
    {
    usage(argv[0]);
    return 0;
    }

    lpFunc == 0;

 for (function_count = 0; function_count < NUMBER_OF_FUNCTIONS; function_count++)
     {
     if (!strcmp(argv[1], szFunctions[function_count]))
        {
         lpFunc = lpFunctions[function_count];      /* compiler error here */
         printf("\nFunction %s selected",szFunctions[function_count]);
         lpFunc();
         break;
        }
     }
     if (lpFunc == 0)
        {
         printf("\nInvalid Function");
        }
return 0;
}

void usage(char *szModuleName)
{
 printf("\nUsage: %s <FUNCTION_NAME> one,two,three", szModuleName);
}

void one(void)
{
 printf("\nFirst function called");
}

void two(void)
{
 printf("\nSecond function called");
}

void three(void)
{
 printf("\nThird function called");
}

ressem

1
if (argc != 2)
{
usage(argv[0]);
return 0;
}

lpFunc == 0; // guess you mean lpFunc = 0


2
void (*lpFunctions[NUMBER_OF_FUNCTIONS])(void) = { one, two, three };

flav0rflav

Just to expand on the solution,

You declared the lpFunctions variable as an array of void pointers. Then you tried to assign one of its members to a function pointer variable. ressem declares the array correctly. Other people may have been tempted to using a cast during the assignment, but that's just masking the compiler error/warning. My own preferred technique is to use a typedef for the pointer-to-function type, as it makes it a little simpler to see the variables and their types.

Martyr

Thanks for the help lads, I'll see if all works out later.
ressem, you were right about assignment.

Typedef

How about this?

#include <stdio.h>


void one(void){
	printf("One called\n");
return;
};

void two(void){
	printf("Two called\n");
return;
};

void (*aggregate[])(void)={one,two};


int main(int argc,char**argv){

	int a;
	void (*dref)(void);

	printf("Running\n");
	for(a=0;a<2;a++){
		dref=aggregate[a];
		dref();
	}
return 0;
};