19.Write a program in c language to print the pattern of a right angled triangle using a for loop.

This C program creates a right triangle pattern where each line displays numbers in increments of 1 up to the line number. Use nested "for" loops to control the number of lines and numbers displayed in each line, creating the desired pattern.

#include <stdio.h>
int main()
 {
    int i, j, rows;  // Declare variables i,j for loop counters and rows for user input.

    printf("\n Enter a total number of rows :\n ");  // show this message to user for input.
    scanf("%d", &rows);  // Read and store the value of rows from the user.

    for (i=1; i<=rows;i++)
    { 
 		// Starting a loop to generate number of rows.
        for (j = 1; j <= i; j++)  // Nested for loop to print numbers based on the current row.
				printf("%d",j);  // show the value of 'j'.
        printf("\n");  
    }
 return(0);
}

Program Explanation
In the above loop, the variable i is initialized to 1 and the loop will continue until i is less than or equal to the value of the "rows" variable. In each iteration of the outer loop, another loop is started with variable j, which starts at 1 and continues until j is less than or equal to the value of i.
On each iteration of the inner loop, the printf() function prints the value of j to the console. This value is printed j times because the value of j is incremented by 1 on each iteration of the inner loop.
After the inner loop completes, the outer loop prints the newline code (\n) to create a new line.
Finally, the outer loop increments the value of i by 1 and this process repeats until i<= rows are invalid.