Reg Function pointers

[sowmi]

Hi All,

I am trying to implement the concept of function pointer in C++.
While compiling i got some errors which I couldnt figure out the reason .
So,Please let me know what changes should be done for resolving that error.

I am trying to execute one particular command function when the commandis pressed.Likewis e, I have 100 commands and whenever the commands are pressed the corresponding function + arguements should be passed and the function pointer should execute the command.


Below are my code,


[/code]
command.h
**********
#define FUNCPTR void *
#define MAX_NUM_COMMAND S 3

typedef struct
{
char command[LINELEN]; /* name of the command */
char parm1[LINELEN]; /*parameter 1 */
char parm2[LINELEN]; /*parameter 2 */

} ExeCmd_s;
class FunctionEntry
{

public:
char* commandString;
FUNCPTR pFun;
int SearchCommand(c har* command);
};
FunctionEntry funArr[MAX_NUM_COMMAND S]=
{
{"aaa",(FUNCPTR )aaa},
{"bbb", (FUNCPTR)bbb},
{"ccc",(FUNCPTR )ccc}

};
enum commandName
{
aaa = 0,
bbb
};


command.c
**********
void void Execute ()
{
.........
.........
Execmd execmd;
FunctionEntry command;
int rc;
if(0 != SearchCommand(e xeCmd.command))
{
command = FunctionEntry.S earchCommand(ex eCmd.command);
switch((int)com mand.numOfArgue ments)
{
case Zero :
rc = ((command.pFun) ();
break;
case one:
rc = ((command.pFun) ,exeCmd.parm1);
break;
}
}
else
{
printf("No match");
}

}



//Function to search and returns the index of the command

int FunctionEntry :: SearchCommand(c har* command)
{

ExeCmd_s exeCmd; //already had a Structure where I am extracting the commandname..
int index = 0;
while(index < MAX_NUM_COMMAND S)
{
if(strcmp(exeCm d.command,funAr r[index]) == 0)
{
return &funArr[index];
}
index++;
}
return NULL;
}
[/code]




Please let me know where i should change the code.
Expecting some solutions for this code ASAP .

Thanks,
Sowmi

[weaknessforcats]

The first thing to do is remove all of the type casts.

The second thing to do is read about pointers in a C++ textbook. I recommend "C++ Primer Plus" by Stephen Prata or the "C Primer Plus" by the Waite Group.

Basicall, a pointer is a variable. However, the value inside the variable can only be the address of something else. You must a) put an address in the pointer and b) you must de-reference the pointer in order to use the something else:

[code=c]
int a = 10;
int* prtr; //this is the pointer
ptr = &a; //the address of a is put inside the pointer
cout << ptr; //you see the address inside th pointer
cout << *ptr; //you see the value of a as 10
*ptr = 20; //change the value to 20 at the address inside the pointer
//this changes a to 20
cout << *ptr; //you see the value of a as 20.
[/code]

Get comfortable with this type of pointer before attempting a function pointer.

There is simple too much wrong with your code for me to fix it.