#include<stdio.h>

// Function to transpose a square matrix
void Transpose(int n, int arr[n][n]) {
    // Loop through each element above the main diagonal
    for(int i=0; i<n; i++){
        for(int j=i+1; j<n; j++){
            // Swap the element at (i, j) with the element at (j, i)
            int temp = arr[j][i];
            arr[j][i] = arr[i][j];
            arr[i][j] = temp;
        }
    }
}

// Function to reverse each row of a square matrix
void ReverseRows(int n, int arr[n][n]) {
    // Loop through each row
    for(int i=0; i<n; i++){
        // Loop through each element in the first half of the row
        // and swap it with the corresponding element in the second half
        for(int j=0, k=n-1; j<k; j++, k--){
            int temp = arr[i][j];
            arr[i][j] = arr[i][k];
            arr[i][k] = temp;
        }
    }
}

int main() {
    // Read the size of the matrix from the user
    int n;
    printf("Enter the size of the array:\n");
    scanf("%d",&n);

    // Declare a square matrix of size n
    int arr[n][n];

    // Read the elements of the matrix from the user
    printf("Enter array elements:\n");
    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            scanf("%d",&arr[i][j]);
        }
    }

    // Transpose the matrix and then reverse each row
    // This effectively rotates the matrix 90 degrees clockwise
    Transpose(n,arr);
    ReverseRows(n,arr);

    // Print the rotated matrix
    printf("The array after being rotated 90 degree is:\n");
    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            printf("%d ",arr[i][j]);
        }
        printf("\n");
    }

    return 0;
}

/*


This program reads a square matrix of size n from the user, rotates the matrix 90 degrees clockwise, and then prints the rotated matrix. The rotation is done in two steps: first, the matrix is transposed, and then each row of the transposed matrix is reversed. These operations are done in-place, meaning they directly modify the original matrix without needing to create a new matrix. This makes the program more memory-efficient, especially for large matrices.

*/
by

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#include <stdio.h>
int main()
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About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}