Explanation of arguments/parameters in Functions

I am not 100% sure about functions at the moment.

[1] Declare function above main.

Code:

int qcheck(int holdans, int *p);

[2] Call function:

Code:

qcheck (holdans, &score);

[3] Function definition that is called:

Code:

int qcheck(int holdans, int *p)
{
           code
}

Question.
Does 1 and 2 always have to match exactly?



p.s I love pointers (when I understand them), they can be so simple and short.

Yes, they should be.
You are asking if 1 and 3 have to match exactly, right?

Originally Posted by hellogamesmaste

Does 1 and 2 always have to match exactly?

That depends on what you mean by "match exactly". For example, a parameter could be declared as a const int*, but you can pass a pointer to a non-const int as a corresponding argument.

2 is coded wrong. It returns an int, therefore assign the return value to an int.

Originally Posted by Dino

2 is coded wrong. It returns an int, therefore assign the return value to an int.

It is not a requirement to read the return value of a function. Do you always assign the return value of printf() to a variable when you use it?

The return value is optional... it's correct code. Whether it's semantically correct or not, we can only guess.

I ask because my program didn't work and I didn't know why.

In [1] I had:

Code:

int qcheck(int , int *p);

in [3] I had:

Code:

int qcheck(holdans, int *p)

So I kept getting error messages because the int was missing in 3.


Another question, regarding pointers in functions.

Usually you do the following:

int a, *p
p = &a
*p = 10

However, with functions, you can leave out the p = &a by:

Code:

int qcheck(int , int *p);

Code:

qcheck (holdans, &score);

Passing the &score into a calling function to a called function that has int *p as a parameter, passing p to &score is therefore not necessary. Does the function do this automatically?

I got really confused and kept doing in main:

Code:

p=&score

and then tried to

Code:

qcheck(holdans, p)

because I thought it would pass the address.

I got it working in the end, but I kept thinking of pointing p to &score. Obviously this must not be necessary when passing pointers to functions.

So I kept getting error messages because the int was missing in 3.

yeah - you need to put the type in both places

However, with functions, you can leave out the p = &a by:

Whenever you pass a value to a function, the values you pass in are assigned to the local variables specified in the parameters. In other words, if I have a function

Code:

add(int a, int b)

that I call from main, main shouldn't be manually assigning anything to a and b, because they're not in scope for main. All you do is call the function as

Code:

add(1, 3)

and the values 1 and 3 are assigned to a and b as local variables inside the function. The same goes for pointer. If you accept a pointer as a parameter, whatever address is passed in is assigned to that pointer.

Ahh thank you. That has made it clearer. I just hope it sticks