Using Pointers in a function

greeneyehawk · 06-24-2009, 09:04 PM

I am learning C, and am am trying to create my own "swap" function for practice that takes in two numbers and puts them in two different variables. I then set one pointer to each. This is where I get stuck.

What should I pass into the function parameters: by this I mean do I pass say, *num1, or the address it points to, num1. I am confused. Please provide code examples.

Thanks

Sebastiani · 06-24-2009, 09:10 PM

Yes, the address.

Code:

void swap( int* a, int* b );

int main( void )
{
	int 
		i, 
		j;
	swap( &i, &j );
	int
		* p = &i, 
		* q = &j;
	swap( p, q );	
}

MK27 · 06-24-2009, 09:10 PM

Quote:

Originally Posted by greeneyehawk

Please provide code examples.

It will probably be easier if you provide code examples. But I think Sebastiani might have nailed this one.

ITAmember · 06-24-2009, 09:11 PM

I'm assuming you know how memory addresses work. I'm also assuming other people will post code for you. This is just how I learned how pointer operators work.

* gets the value at an address
& gets the address of a value

That's it. They really aren't that complicated once you understand them

greeneyehawk · 06-24-2009, 09:40 PM

Thank you so much, I got it.

06-24-2009, 09:04 PM	#1
greeneyehawk Registered User Join Date: Jun 2009 Posts: 2	Using Pointers in a function I am learning C, and am am trying to create my own "swap" function for practice that takes in two numbers and puts them in two different variables. I then set one pointer to each. This is where I get stuck. What should I pass into the function parameters: by this I mean do I pass say, *num1, or the address it points to, num1. I am confused. Please provide code examples. Thanks
greeneyehawk is offline

06-24-2009, 09:10 PM	#2
Sebastiani Guest Join Date: Aug 2001 Posts: 4,923	Yes, the address. Code: void swap( int* a, int* b ); int main( void ) { int i, j; swap( &i, &j ); int * p = &i, * q = &j; swap( p, q ); }
Sebastiani is offline

06-24-2009, 09:11 PM	#4
ITAmember Registered User Join Date: Mar 2009 Location: Nebraska Posts: 72	I'm assuming you know how memory addresses work. I'm also assuming other people will post code for you. This is just how I learned how pointer operators work. * gets the value at an address & gets the address of a value That's it. They really aren't that complicated once you understand them __________________ Super amazing game!
ITAmember is offline

06-24-2009, 09:40 PM	#5
greeneyehawk Registered User Join Date: Jun 2009 Posts: 2	Thanks! Thank you so much, I got it.
greeneyehawk is offline

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