# Program to print the Diagonals of a Matrix

Given a 2D square matrix, print the Principal and Secondary diagonals.

Examples :

```Input:
4
1 2 3 4
4 3 2 1
7 8 9 6
6 5 4 3
Output:
Principal Diagonal: 1, 3, 9, 3
Secondary Diagonal: 4, 3, 8, 6

Input:
3
1 1 1
1 1 1
1 1 1
Output:
Principal Diagonal: 1, 1, 1
Secondary Diagonal: 1, 1, 1
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

For example, consider the following 4 X 4 input matrix.

```A00 A01 A02 A03
A10 A11 A12 A13
A20 A21 A22 A23
A30 A31 A32 A33
```
1. The primary diagonal is formed by the elements A00, A11, A22, A33.

Condition for Principal Diagonal:

`The row-column condition is row = column.`
2. The secondary diagonal is formed by the elements A03, A12, A21, A30.

Condition for Secondary Diagonal:

`The row-column condition is row = numberOfRows - column -1.`

In this method, we use two loops i.e. a loop for columns and a loop for rows and in the inner loop we check for the condition stated above.

## C++

 `// C++ Program to print the Diagonals of a Matrix ` ` `  `#include ` `using` `namespace` `std; ` ` `  `const` `int` `MAX = 100; ` ` `  `// Function to print the Principal Diagonal ` `void` `printPrincipalDiagonal(``int` `mat[][MAX], ``int` `n) ` `{ ` `    ``cout << ``"Principal Diagonal: "``; ` ` `  `    ``for` `(``int` `i = 0; i < n; i++) { ` `        ``for` `(``int` `j = 0; j < n; j++) { ` ` `  `            ``// Condition for principal diagonal ` `            ``if` `(i == j) ` `                ``cout << mat[i][j] << ``", "``; ` `        ``} ` `    ``} ` `    ``cout << endl; ` `} ` ` `  `// Function to print the Secondary Diagonal ` `void` `printSecondaryDiagonal(``int` `mat[][MAX], ``int` `n) ` `{ ` `    ``cout << ``"Secondary Diagonal: "``; ` ` `  `    ``for` `(``int` `i = 0; i < n; i++) { ` `        ``for` `(``int` `j = 0; j < n; j++) { ` ` `  `            ``// Condition for secondary diagonal ` `            ``if` `((i + j) == (n - 1)) ` `                ``cout << mat[i][j] << ``", "``; ` `        ``} ` `    ``} ` `    ``cout << endl; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `n = 4; ` `    ``int` `a[][MAX] = { { 1, 2, 3, 4 }, ` `                     ``{ 5, 6, 7, 8 }, ` `                     ``{ 1, 2, 3, 4 }, ` `                     ``{ 5, 6, 7, 8 } }; ` ` `  `    ``printPrincipalDiagonal(a, n); ` `    ``printSecondaryDiagonal(a, n); ` `    ``return` `0; ` `} `

## Java

 `// Java Program to print the Diagonals of a Matrix ` `class` `GFG  ` `{ ` `    ``static` `int` `MAX = ``100``; ` ` `  `    ``// Function to print the Principal Diagonal ` `    ``static` `void` `printPrincipalDiagonal(``int` `mat[][], ``int` `n) ` `    ``{ ` `        ``System.out.print(``"Principal Diagonal: "``); ` ` `  `        ``for` `(``int` `i = ``0``; i < n; i++) ` `        ``{ ` `            ``for` `(``int` `j = ``0``; j < n; j++)  ` `            ``{ ` ` `  `                ``// Condition for principal diagonal ` `                ``if` `(i == j) ` `                ``{ ` `                    ``System.out.print(mat[i][j] + ``", "``); ` `                ``} ` `            ``} ` `        ``} ` `        ``System.out.println(``""``); ` `    ``} ` ` `  `    ``// Function to print the Secondary Diagonal ` `    ``static` `void` `printSecondaryDiagonal(``int` `mat[][], ``int` `n) ` `    ``{ ` `        ``System.out.print(``"Secondary Diagonal: "``); ` ` `  `        ``for` `(``int` `i = ``0``; i < n; i++)  ` `        ``{ ` `            ``for` `(``int` `j = ``0``; j < n; j++)  ` `            ``{ ` ` `  `                ``// Condition for secondary diagonal ` `                ``if` `((i + j) == (n - ``1``))  ` `                ``{ ` `                    ``System.out.print(mat[i][j] + ``", "``); ` `                ``} ` `            ``} ` `        ``} ` `        ``System.out.println(``""``); ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String args[]) ` `    ``{ ` `        ``int` `n = ``4``; ` `        ``int` `a[][] = {{``1``, ``2``, ``3``, ``4``}, ` `                     ``{``5``, ``6``, ``7``, ``8``}, ` `                     ``{``1``, ``2``, ``3``, ``4``}, ` `                     ``{``5``, ``6``, ``7``, ``8``}}; ` ` `  `        ``printPrincipalDiagonal(a, n); ` `        ``printSecondaryDiagonal(a, n); ` `    ``} ` `} ` ` `  `// This code is contributed by Rajput-Ji `

## Python3

 `# Python3 Program to prthe Diagonals of a Matrix ` `MAX` `=` `100` ` `  `# Function to prthe Principal Diagonal ` `def` `printPrincipalDiagonal(mat, n): ` `    ``print``(``"Principal Diagonal: "``, end ``=` `"") ` ` `  `    ``for` `i ``in` `range``(n): ` `        ``for` `j ``in` `range``(n): ` ` `  `            ``# Condition for principal diagonal ` `            ``if` `(i ``=``=` `j): ` `                ``print``(mat[i][j], end ``=` `", "``) ` `    ``print``() ` ` `  `# Function to prthe Secondary Diagonal ` `def` `printSecondaryDiagonal(mat, n): ` `    ``print``(``"Secondary Diagonal: "``, end ``=` `"") ` ` `  `    ``for` `i ``in` `range``(n): ` `        ``for` `j ``in` `range``(n): ` ` `  `            ``# Condition for secondary diagonal ` `            ``if` `((i ``+` `j) ``=``=` `(n ``-` `1``)): ` `                ``print``(mat[i][j], end ``=` `", "``) ` `    ``print``() ` ` `  `# Driver code ` `n ``=` `4` `a ``=` `[[ ``1``, ``2``, ``3``, ``4` `], ` `     ``[ ``5``, ``6``, ``7``, ``8` `], ` `     ``[ ``1``, ``2``, ``3``, ``4` `], ` `     ``[ ``5``, ``6``, ``7``, ``8` `]] ` ` `  `printPrincipalDiagonal(a, n) ` `printSecondaryDiagonal(a, n) ` ` `  `# This code is contributed by Mohit Kumar `

## C#

 `// C# Program to print the Diagonals of a Matrix ` `using` `System; ` `     `  `class` `GFG  ` `{ ` `    ``static` `int` `MAX = 100; ` ` `  `    ``// Function to print the Principal Diagonal ` `    ``static` `void` `printPrincipalDiagonal(``int` `[,]mat, ``int` `n) ` `    ``{ ` `        ``Console.Write(``"Principal Diagonal: "``); ` ` `  `        ``for` `(``int` `i = 0; i < n; i++) ` `        ``{ ` `            ``for` `(``int` `j = 0; j < n; j++)  ` `            ``{ ` ` `  `                ``// Condition for principal diagonal ` `                ``if` `(i == j) ` `                ``{ ` `                    ``Console.Write(mat[i, j] + ``", "``); ` `                ``} ` `            ``} ` `        ``} ` `        ``Console.WriteLine(``""``); ` `    ``} ` ` `  `    ``// Function to print the Secondary Diagonal ` `    ``static` `void` `printSecondaryDiagonal(``int` `[,]mat, ``int` `n) ` `    ``{ ` `        ``Console.Write(``"Secondary Diagonal: "``); ` ` `  `        ``for` `(``int` `i = 0; i < n; i++)  ` `        ``{ ` `            ``for` `(``int` `j = 0; j < n; j++)  ` `            ``{ ` ` `  `                ``// Condition for secondary diagonal ` `                ``if` `((i + j) == (n - 1))  ` `                ``{ ` `                    ``Console.Write(mat[i, j] + ``", "``); ` `                ``} ` `            ``} ` `        ``} ` `        ``Console.WriteLine(``""``); ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main(String []args) ` `    ``{ ` `        ``int` `n = 4; ` `        ``int` `[,]a = {{1, 2, 3, 4}, ` `                    ``{5, 6, 7, 8}, ` `                    ``{1, 2, 3, 4}, ` `                    ``{5, 6, 7, 8}}; ` ` `  `        ``printPrincipalDiagonal(a, n); ` `        ``printSecondaryDiagonal(a, n); ` `    ``} ` `} ` ` `  `// This code is contributed by 29AjayKumar `

Output:

```Principal Diagonal: 1, 6, 3, 8,
Secondary Diagonal: 4, 7, 2, 5,
```

My Personal Notes arrow_drop_up Talk is cheap Show me the code -)

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