C Program to Reverse an Array

In this article we will show you, How to write a C Program to Reverse an Array using While Loop, For loop, Functions and Recursion with example.

C Program to Reverse an Array using While Loop

This C program allows the user to enter the array size and the array elements and then, this program will reverse the given array elements using While Loop in C

/* C Program to Reverse an Array using While loop */
#include<stdio.h>
 
int main() 
{
   int a[100], i, j, Size, Temp;
 
   printf("\nPlease Enter the size of an array: ");
   scanf("%d",&Size);
 
   //Inserting elements into the array
   for (i = 0; i < Size; i++) 
   {
      scanf("%d", &a[i]);
   }
 
   j = i - 1;   // Assigning j to Last array element
   i = 0;       // Assigning i to first array element
 
   while (i < j) 
   {
      Temp = a[i];
      a[i] = a[j];
      a[j] = Temp;
      i++;             
      j--;         
   }
 
   printf("\nResult of an Reverse array is: ");
   for (i = 0; i < Size; i++) 
   {
      printf("%d \t", a[i]);
   }
 
   return 0;
}

OUTPUT

ANALYSIS
Following statements will ask the user to enter the array size and assign the user entered value to Size variable

   printf("\nPlease Enter the size of an array: ");
   scanf("%d",&Size);

Below For loop will help to iterate each and every cell present in the a[5] array. For loop iteration will start at 0 and the condition inside the for loops (i < Size) will ensure the compiler, not to exceed the array limit.

Scanf statement inside the for loop will store the user entered values in every individual array element such as a[0], a[1], a[2], a[3] and a[4]

   //Inserting elements into the array
   for (i = 0; i < Size; i++) 
   {
      scanf("%d", &a[i]);
   }

Next, The Condition inside the While loop will make sure that, the i value is less than j. Inside the while loop we performed the Swapping with the help of third variable. If you want to perform the swapping without any temporary variables then please refer Swapping without using Temp Variable article.

Last, We used the for loop to print the reversed array to the console output.

   for (i = 0; i < Size; i++) 
   {
      printf("%d \t", a[i]);
   }

C Program to Reverse an Array using For Loop

This program allows the user to enter the array size and the array elements and then, this program will reverse the given array elements using For Loop

/* C Program to Reverse an Array using For Loop */
#include<stdio.h>
 
int main() 
{
   int a[100], b[100], i, j, Size;
 
   printf("\nPlease Enter the size of an array: ");
   scanf("%d",&Size);
 
   //Inserting elements into the array
   for (i = 0; i < Size; i++) 
   {
      scanf("%d", &a[i]);
   }
 
   for(i = Size-1, j = 0; i >= 0; i--, j++) 
   {
      b[j] = a[i];     
   }
 
   printf("\nResult of an Reverse array is: ");
   for (i = 0; i < Size; i++) 
   {
      printf("%d \t", b[i]);
   }
 
   return 0;
}

ANALYSIS: In this example, we just replaced the while loop with For Loop. Apart from that, everything is same.

OUTPUT

C Program to Reverse an Array using Functions

This program allows the user to enter the array size and the array elements and then, this program will reverse the given array elements using Functions

//  C Program to Reverse an Array using Functions
#include<stdio.h>
void ArrayReverese(int a[], int Start, int End);
void printArray(int a[], int Size);

int main() 
{
   int a[100], i, Size;
 
   printf("\nPlease Enter the size of an array: ");
   scanf("%d",&Size);
   
   //Inserting elements into the Declared Array
   for (i = 0; i < Size; i++) 
   {
      scanf("%d", &a[i]);
   }

    ArrayReverese(a, 0, Size-1);//Array Reverse
    printf("Result of an Reverse array is: \n");
    printArray(a, Size); //Printing Array    
    return 0;
}

/* Function to Reverse the Given Array */
void ArrayReverese(int a[], int Start, int End)
{
   int Temp;
   while (Start < End) 
   {
      Temp = a[Start];
      a[Start] = a[End];
      a[End] = Temp;
      Start++;             
      End--;         
   }  
}     

/* Function to print the Array Output */
void printArray(int a[], int Size)
{
  int i;
  for (i = 0; i < Size; i++) 
   {
      printf("%d ", a[i]);
   }
  printf("\n");
}

OUTPUT

ANALYSIS
When the compiler reaches to ArrayReverse (a, 0, Size – 1) line in main() program, compiler will immediately jump to the following function and executed the code inside that function. Here, it is reversing the array

void ArrayReverese(int a[], int Start, int End)

Next, we also declared one more function to print the Array. When the compiler reaches to printArray (a, Size) line in main() program, compiler will immediately jump to the following function and executed the code inside that function.

void printArray(int a[], int Size)

W already explained the Code or logic in the above example.

C Program to Reverse an Array using Recursion

This program allows the user to enter the array size and the array elements and then, this program will reverse the given array elements using Recursion

//  C Program to Reverse an Array using Recursion
#include<stdio.h>

void ArrayReverese(int a[], int Start, int End);
void printArray(int a[], int Size);

int main() 
{
   int a[100], i, Size;
   printf("\nPlease Enter the size of an array: ");
   scanf("%d",&Size);
   //Inserting elements into the Declared Array
   for (i = 0; i < Size; i++) 
   {
      scanf("%d", &a[i]);
   }
    ArrayReverese(a, 0, Size-1); //Array Reverse
    printf("Result of an Reverse array is: \n");
    printArray(a, Size); //Printing Array   
    return 0;
}

/* Function to Reverse the Given Array */
void ArrayReverese(int a[], int Start, int End)
{
   int Temp;
   if (Start < End)
   {
      Temp = a[Start];
      a[Start] = a[End];
      a[End] = Temp;
      ArrayReverese(a, Start + 1, End - 1);        
   }  
}     

/* Function to print the Array Output */
void printArray(int a[], int Size)
{
  int i;
  for (i = 0; i < Size; i++) 
   {
      printf("%d ", a[i]);
   }
  printf("\n");
}

OUTPUT

void ArrayReverese(int a[], int Start, int End)

Within the above function, If statement will check whether the Start position is less than End position. If the condition is TRUE then only statemnets inside this If block will be executed.

Inside the If statement we written following statement to call the function Recursively with updated value. If you miss this statement then, after completing the first line it will terminate.

ArrayReverese(a, Start + 1, End - 1);

void printArray(int a[], int Size)

We already explained the Code or logic in the above example.

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