# Upper triangular matrix in C | Lower triangular matrix in C

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studymite

## C program to check whether a matrix is upper triangular and lower triangular without using an array

Here, We’ll learn to write a program to check whether the given matrix is upper triangular or not in C programming language.

Upper Triangular Matrix: An upper triangular matrix is a special type of matrix that has all of its elements below the main diagonal (the diagonal from the top left to the bottom right of the matrix) set to zero.

###### Source: https://commons.wikimedia.org/wiki/File:Triangular_matrix.svg
1. Initialize variables `is_uppr` and `is_lowr` to 1.
2. Take input for the number of rows and the matrix.
3. Iterate through the matrix.
4. If any element below the main diagonal is non-zero, set `is_uppr` to 0.
5. If any element above the main diagonal is non-zero, set `is_lowr` to 0.
6. If `is_uppr` or `is_lowr` is 1, print "Upper Triangular".
7. Else, print "Not Upper Triangular".

Code:

``````#include <stdio.h>

int main()
{
int n, i, j, is_uppr = 1, is_lowr = 1, a;

printf("Enter the number of rows:: ");
scanf("%d", &n);

printf("Enter the Array::\n");
for (i = 0; i < n; i++)
{
for (j = 0; j < n; j++)
{
scanf("%d", &a);
if (j > i && a != 0) //Check for upper triangular condition
is_uppr = 0;
if (j < i && a != 0) //Check for lower triangular condition
is_lowr = 0;
}
}
if (is_uppr == 1 || is_lowr == 1)
printf("Upper Triangular\n");
else
printf("Not Upper Triangular\n");

return 0;
}

``````

Output

``````Enter the number of rows:: 4
Enter the Array::
1 0 0 0
0 2 0 0
0 0 3 0
0 0 0 4
Upper Triangular

Enter the number of rows:: 3
Enter the Array::
1 2 0
3 4 5
6 7 8
Not Upper Triangular

``````