Thread: pointers

Hi all,

Can you confirm im passing my pointer to and from the function correctly? In some examples I have seen them pass the address - I have also passed address?

Lastly I have read the only math you can perform on a pointer is ++ and --. After thinking about this, I think the mean you can only perform these operations on the address but not the pointer?

I have included my pointer example below for your review.

Code:

#include<stdio.h> 

char add_number(char *ptr)
{
	*ptr = *ptr + 10;
	return *ptr;

}

int main()
{
	char result;
	char name = 2;
	char *ptr;
	ptr = &name;
	
                result = add_number(ptr);
	printf("%d\n", result);
	
}

Hi,

Thanks for your help and tips. Im working in an embedded enviroment at the minute and you guys and girls seem to be the most helpful on C and its nuts and bolts.

Im very black and white in my coding, I either use pointers or I dont. Previously I avoided them like the plauge. Now im making an effort to write all my programs using mostly pointers - Is this correct?. For time critical operations, if the above example was writen with or without pointers, is the speed much different? I now we are probably talking pico seconds, but is there a speed increase (faster) with pointers?

Look forward to your reply.

RocketMan

Originally Posted by Elysia

Avoid allocating things on the heap.

Unless of course you need a lot of memory or you don't know how much memory you need at compile time.

Originally Posted by RocketMan

Code:

#include<stdio.h> 

char add_number(char *ptr)
{
	*ptr = *ptr + 10;
	return *ptr;

}

int main()
{
	char result;
	char name = 2;
	char *ptr;
	ptr = &name;
	
                result = add_number(ptr);
	printf("%d\n", result);
	
}

Um, what's this doing? What is result, there's no type with it? How do you assign an int, 2, to a chartype var, name? Result looks like it need to be declared with type int. What are you trying to do?

-CG20

Originally Posted by CodeGeek20

Um, what's this doing? What is result, there's no type with it? How do you assign an int, 2, to a chartype var, name? Result looks like it need to be declared with type int. What are you trying to do?

-CG20

char is not only used for text characters, but it's an integer type with a range [-127, 128] or [0, 255] for unsigned char. If that range it all you need for what you need to do, then why waste extra space with 2, 4, or 8 byte variables?

Hi all,

Thanks for all your feedback.

The example was just random, and was just used to explain my point.

As for using char, I use these mostly in embedded c because its kind off a small int and uses less program memory. This is quite important in microcontrollers, but in pc programming most people just use ints.

Thanks again for your tips.

Cheers

RocketMan.