{"id":743,"date":"2024-10-19T13:23:17","date_gmt":"2024-10-19T07:53:17","guid":{"rendered":"https:\/\/codexplained.in\/?p=743"},"modified":"2025-11-24T15:39:17","modified_gmt":"2025-11-24T10:09:17","slug":"reverse-an-array","status":"publish","type":"post","link":"https:\/\/codexplained.in\/?p=743","title":{"rendered":"Reverse an Array"},"content":{"rendered":"
\n#include <stdio.h>\n\nvoid reverseArray(int arr[], int size) {\n    int start = 0;               \/\/ Initialize start index\n    int end = size - 1;         \/\/ Initialize end index\n    int temp;                   \/\/ Temporary variable for swapping\n\n    \/\/ Loop until the start index is less than the end index\n    while (start < end) {\n        \/\/ Swap the elements at start and end indices\n        temp = arr[start];       \/\/ Store the start element in temp\n        arr[start] = arr[end];   \/\/ Assign the end element to start position\n        arr[end] = temp;         \/\/ Assign temp (original start) to end position\n\n        \/\/ Move indices towards the center\n        start++;                  \/\/ Increment start index\n        end--;                    \/\/ Decrement end index\n    }\n}\n\nint main() {\n    int arr[] = {1, 2, 3, 4, 5}; \/\/ An array to be reversed\n    int size = sizeof(arr) \/ sizeof(arr[0]); \/\/ Calculate the size of the array\n\n    printf("Original array: ");\n    for (int i = 0; i < size; i++) {\n        printf("%d ", arr[i]);   \/\/ Print original array\n    }\n    printf("\\n");\n\n    reverseArray(arr, size);      \/\/ Call the function to reverse the array\n\n    printf("Reversed array: ");\n    for (int i = 0; i < size; i++) {\n        printf("%d ", arr[i]);   \/\/ Print the reversed array\n    }\n    printf("\\n");\n\n    return 0;                     \/\/ End of program\n}\n\n<\/pre><\/div>\n\n\n
Explanation<\/h3>\n\n\n\n
    \n
  1. Include Header File<\/strong>:cCopy code#include <stdio.h> <\/code>This line includes the standard input-output library, which allows us to use functions like printf<\/code>.<\/li>\n\n\n\n
  2. Function Definition<\/strong>:cCopy codevoid reverseArray(int arr[], int size) <\/code>Here, we define a function called reverseArray<\/code>. It takes two parameters: an array of integers arr<\/code> and its size<\/code>. This function will handle the logic for reversing the array.<\/li>\n\n\n\n
  3. Initialize Indices<\/strong>:cCopy codeint start = 0; int end = size - 1; <\/code>We set two indices: start<\/code> begins at the first element (index 0), and end<\/code> starts at the last element (index size - 1<\/code>).<\/li>\n\n\n\n
  4. While Loop<\/strong>:cCopy codewhile (start < end) { <\/code>This loop continues as long as the start<\/code> index is less than the end<\/code> index. This condition ensures that we only swap elements until we reach the middle of the array.<\/li>\n\n\n\n
  5. Swapping Elements<\/strong>:cCopy codetemp = arr[start]; arr[start] = arr[end]; arr[end] = temp; <\/code>Inside the loop, we perform the following steps:\n
      \n
    • Store the value at the start<\/code> index in a temporary variable temp<\/code>.<\/li>\n\n\n\n
    • Set the value at the end<\/code> index to the start<\/code> index.<\/li>\n\n\n\n
    • Finally, assign the value in temp<\/code> (originally from start<\/code>) to the end<\/code> index. This effectively swaps the two elements.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
    • Update Indices<\/strong>:cCopy codestart++; end--; <\/code>After swapping, we move the start<\/code> index one step to the right (increment) and the end<\/code> index one step to the left (decrement) to continue the process towards the center of the array.<\/li>\n\n\n\n
    • Main Function<\/strong>:cCopy codeint main() { <\/code>This is the starting point of our program. Here, we declare and initialize an array arr<\/code>.<\/li>\n\n\n\n
    • Calculate Array Size<\/strong>:cCopy codeint size = sizeof(arr) \/ sizeof(arr[0]); <\/code>We calculate the number of elements in the array by dividing the total size of the array by the size of one element.<\/li>\n\n\n\n
    • Print Original Array<\/strong>: We loop through the array and print each element to show its original order.<\/li>\n\n\n\n
    • Call the Reverse Function<\/strong>:cCopy codereverseArray(arr, size); <\/code>We call our reverseArray<\/code> function, passing in the array and its size.<\/li>\n\n\n\n
    • Print Reversed Array<\/strong>: Finally, we print the elements of the array again, but this time in their reversed order.<\/li>\n<\/ol>\n\n\n\n
      Output of the Given Code<\/h2>\n\n\n\n
      Original array: 1 2 3 4 5
      Reversed array: 5 4 3 2 1<\/p>\n