Reversing an array using pointers

[asilvester635]

I have this program that makes and populates an array. Then it is sent to a function called reverse, which reverses the order in the array. The compiler keeps giving errors. I'm not quite sure why.


CODE

void reverse(int* array, int size) {

	for (int i = 0; i < size/2; i++) {
		int temp = array[i];
		array[i] = array[size-i];
		array[size-i] = temp;
	} // end of for loop

} // end of reverse 


int main( int argc, char** argv ) {

	int array[8];

	// get and print size of the array
	int size = sizeof(array) / sizeof(array[0]);
	printf("Size is %d\n", size);

	// populate array
	for (int i = 0; i < size; i++) {
		array[i] = i;
	} // end of for loop

	// display array before reversing
	for (int i = 0; i < size; i++) {
		printf("%d ", array[i]);
	} // end of for loop

	// new line
	printf("\n");

	// reverse the array
	reverse(&array, size);

	// display the array again after reversing
	for (int i = 0;i < size; i++) {
		printf("%d ", array[i]);

	} // end of for loop
} // end of main 

It keeps giving me this error
main.cc:17:14: error: indirection requires pointer operand ('int' invalid)
int temp = *array[i];
^~~~~~~~~
main.cc:18:3: error: indirection requires pointer operand ('int' invalid)
*array[i] = *array[size-i];
^~~~~~~~~
main.cc:18:15: error: indirection requires pointer operand ('int' invalid)
*array[i] = *array[size-i];
^~~~~~~~~~~~~~
main.cc:19:3: error: indirection requires pointer operand ('int' invalid)
*array[size-i] = temp;
^~~~~~~~~~~~~~
4 errors generated.
make: *** [main.o] Error 1

[asilvester635]

I removed the & in front of the array variable when I send it to reverse. Though it gave me what I think is an address location. Below is the output. Why is that? There is no print statement in my code that intentionally prints any address.

Output:
0 1 2 3 4 5 6 7
1412676568 7 6 5 4 3 2 1
[Finished in 0.5s]

[Hengry]

You're getting that number because it's out-of-bound

Notice how the reversed of: 0 1 2 3 4 5 6 7 -> 7 6 5 4 3 2 1 0, but instead you're missing a 0 on the right hand side of the reversed and you have an extra value on the left hand side.

hint:

void reverse(int* array, int size) {

	for (int i = 0; i < size/2; i++) {
		int temp = array[i];
		array[i] = array[size-i];
		array[size-i] = temp;
	} // end of for loop

} // end of reverse  

This is the problem.

[gunnerfunner]

OP: by now I hope you've got all the feedback you wanted:
https://cboard.cprogramming.com/cplusplus-programming/172417-reversing-string-using-pointers.html

[resDesE]

#include "stdio.h"

void reverse(int* array, int size) {
int temp = 0;
for (int i = 0; i <= size/2; i++) {
temp = array[i];
array[i] = array[size-i-1];
array[size-i] = temp;
} // end of for loop

} // end of reverse


int main( int argc, char** argv ) {

int array[8] = {0};

// get and print size of the array
int size = sizeof(array) / sizeof(array[0]);
printf("Size is %d\n", size);

// populate array
for (int i = 0; i < size; i++) {
array[i] = i;
} // end of for loop

// display array before reversing
for (int i = 0; i < size; i++) {
printf("%d ", array[i]);
} // end of for loop

// new line
printf("\n");

// reverse the array
reverse(&array[0], size);

// display the array again after reversing
for (int i = 0;i < size; i++) {
printf("%d ", array[i]);

} // end of for loop
} // end of main



this is my idea

[Flaze07]

@resDesE
it's great to help...but please
use the tags....