Programming Forums > Application Development > C++

Writlaus · Apr 8th, 2006, 7:25 PM

Just a simple question: What is the syntax for writing a function that returns an array? I thought it was something like...

(Toggle Plain Text)

int[] myFunc() {...}

But I don't think that's the right way. Could someone write a simple example please?

jayme · Apr 8th, 2006, 7:36 PM

I had the same question recently.

ill find the link

EDIT: link

I ended up just returning a pointer to the array, it was just as affective in the position I was in.

DaWei · Apr 8th, 2006, 8:55 PM

In C/C++ (unlike some more abstract languages) an array is not an object. It's a collection of objects. You can't return a collection that isn't wrapped in something unitary. That's why C++ introduces class objects like vectors, deques, etc.

jayme · Apr 8th, 2006, 9:00 PM

I just want to clear this up, if you have the choice between using an array and a vector, would it be more wise to choose vectors? From what I've been told, I understand a vector is pretty much an array with more functions, and expandable. So, would arrays be necessary if you know how to use vectors?

DaWei · Apr 9th, 2006, 12:07 AM

If you're using C++, my opinion is: use C++. Only in rare circumstances will the performance hit outweigh the productivity. People use Python and similar all the time without worrying about that, so why not with C++? STL classes for vectors, deques, lists, maps, and so forth, are much easier to use (with just a little study and practice) than ordinary arrays, and relieve the programmer of having to worry so much about sizes (memory allocation) and so forth. A vector is a class that encapsulates an array-like entity and overloads the [] so that one may access it by index. There are other access methods, as well.

InfoGeek · Apr 9th, 2006, 12:08 AM

Use arrays when you're more concerned about efficiency.

DaWei · Apr 9th, 2006, 12:12 AM

Yeah, yeah, whom among you guys ever concerned him/herself with efficiency before? The so-called efficiency is expensive in terms of productivity, which equates to bucks in the real world. If ya gotta, ya gotta, but I don't see any signs of it being of concern to lebenty-zillion percent of the members here.

Jessehk · Apr 9th, 2006, 1:01 AM

I felt like writing some C code.
Just replace malloc with new and free with delete (and the included header files).

(Toggle Plain Text)

#include <stdio.h>
#include <malloc.h>

#define SIZE 10

int *constructArray(int value, int numberOfTimes);

int main(void) {
	int *numbs = constructArray(3, 10);
	int x;

	for(x = 0; x < SIZE; x++)
		printf("%2d%s element of array is %d.\n", x + 1, (x + 1) == 1 ? "st" : "th", numbs[x]);

	free(numbs);

	return 0;
}

int *constructArray(int value, int numberOfTimes) {
	int *result = (int *)malloc(numberOfTimes * sizeof(int));
	int x;

	for(x = 0; x < numberOfTimes; x++)
		*(result + x) = value;

	return result;
}

Writlaus · Apr 9th, 2006, 3:12 AM

Hmm... returning a vector seems to work ok. I just use vector<int> func() {...} instead.

DaWei · Apr 9th, 2006, 8:49 AM

Excellent. Put those guys telling you 'C' on hold, tell 'em the staff is busy, and you'll get back to 'em when you can.

Apr 8th, 2006, 7:25 PM	#1
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	Quick question about arrays and functions Just a simple question: What is the syntax for writing a function that returns an array? I thought it was something like... (Toggle Plain Text) int[] myFunc() {...} int[] myFunc() {...} But I don't think that's the right way. Could someone write a simple example please?

Apr 8th, 2006, 8:55 PM	#3
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	In C/C++ (unlike some more abstract languages) an array is not an object. It's a collection of objects. You can't return a collection that isn't wrapped in something unitary. That's why C++ introduces class objects like vectors, deques, etc. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Apr 9th, 2006, 12:07 AM	#5
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	If you're using C++, my opinion is: use C++. Only in rare circumstances will the performance hit outweigh the productivity. People use Python and similar all the time without worrying about that, so why not with C++? STL classes for vectors, deques, lists, maps, and so forth, are much easier to use (with just a little study and practice) than ordinary arrays, and relieve the programmer of having to worry so much about sizes (memory allocation) and so forth. A vector is a class that encapsulates an array-like entity and overloads the [] so that one may access it by index. There are other access methods, as well. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Apr 9th, 2006, 12:08 AM	#6
InfoGeek Professional Programmer Join Date: Jun 2005 Location: India, The great. Posts: 435 Rep Power: 4	Use arrays when you're more concerned about efficiency. __________________ PFO - My daily dose of technology.

Apr 9th, 2006, 12:12 AM	#7
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Yeah, yeah, whom among you guys ever concerned him/herself with efficiency before? The so-called efficiency is expensive in terms of productivity, which equates to bucks in the real world. If ya gotta, ya gotta, but I don't see any signs of it being of concern to lebenty-zillion percent of the members here. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Apr 9th, 2006, 1:01 AM	#8
Jessehk The Oblivious One Join Date: May 2005 Location: Ontario, Canada Posts: 648 Rep Power: 4	I felt like writing some C code. Just replace malloc with new and free with delete (and the included header files). (Toggle Plain Text) #include <stdio.h> #include <malloc.h> #define SIZE 10 int constructArray(int value, int numberOfTimes); int main(void) { int numbs = constructArray(3, 10); int x; for(x = 0; x < SIZE; x++) printf("%2d%s element of array is %d.\n", x + 1, (x + 1) == 1 ? "st" : "th", numbs[x]); free(numbs); return 0; } int constructArray(int value, int numberOfTimes) { int result = (int )malloc(numberOfTimes sizeof(int)); int x; for(x = 0; x < numberOfTimes; x++) (result + x) = value; return result; } #include <stdio.h> #include <malloc.h> #define SIZE 10 int constructArray(int value, int numberOfTimes); int main(void) { int numbs = constructArray(3, 10); int x; for(x = 0; x < SIZE; x++) printf("%2d%s element of array is %d.\n", x + 1, (x + 1) == 1 ? "st" : "th", numbs[x]); free(numbs); return 0; } int constructArray(int value, int numberOfTimes) { int result = (int )malloc(numberOfTimes * sizeof(int)); int x; for(x = 0; x < numberOfTimes; x++) *(result + x) = value; return result; } __________________ Dr. Zoidberg: [ecstatic] I'm going to a movie... with FRIENDS!

Apr 9th, 2006, 3:12 AM	#9
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	Hmm... returning a vector seems to work ok. I just use vector<int> func() {...} instead.

Apr 9th, 2006, 8:49 AM	#10
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Excellent. Put those guys telling you 'C' on hold, tell 'em the staff is busy, and you'll get back to 'em when you can. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

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Programming Forums > Application Development > C++

Quick question about arrays and functions