Question

How to reverse one dimensional int array in C

Answer 1

#include <stdio.h>
  
#define LEN 7
  
int main(void)
{
    int arr[LEN] = {1, 2, 3, 4, 5, 6, 7};

    for (int i = 0, j = LEN - 1; i < LEN / 2; i++, j--) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }
     
    for (int i = 0; i < LEN; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }
      
    return 0;
}
    
    
      
/*
        
run:
  
arr[0] = 7
arr[1] = 6
arr[2] = 5
arr[3] = 4
arr[4] = 3
arr[5] = 2
arr[6] = 1
 
*/

 

 

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Answer 2

#include <stdio.h>
  
#define LEN 7
  
int main(void)
{
    int arr[LEN] = {1, 2, 3, 4, 5, 6, 7};

    for (int i = 0; i < LEN / 2; i++) {
        int tmp = arr[i];
        arr[i] = arr[LEN - 1 - i];
        arr[LEN - 1 - i] = tmp;
    }
     
    for (int i = 0; i < LEN; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }
      
    return 0;
}
    
    
      
/*
        
run:
  
arr[0] = 7
arr[1] = 6
arr[2] = 5
arr[3] = 4
arr[4] = 3
arr[5] = 2
arr[6] = 1
 
*/

 

 

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Answer 3

#include <stdio.h>
#include <stdlib.h>

void reverse_array(int arr[], int size) {
    for (int i = 0, j = size - 1; i < size / 2; i++, j--) {
         int tmp = arr[i];
         arr[i] = arr[j];
         arr[j] = tmp;
    }
}
 
int main(void)
{
    int arr[] = {1, 2, 3, 4, 5, 6, 7};
    
    int size = sizeof(arr) / sizeof(int); 
    
    reverse_array(arr, size);
  
    for (int i = 0; i < size; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }
  
    return 0;
}




/*
run:

arr[0] = 7
arr[1] = 6
arr[2] = 5
arr[3] = 4
arr[4] = 3
arr[5] = 2
arr[6] = 1

*/

 

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