# Right-angled triangle pattern

You can create useful patterns in c to learn more about loops . To print the pattern we will have to make use of a nested loop. In this tutorial, i will be using for loop to demonstrate how to print patterns. Without much further ado we will look at printing our first pattern which is a right-angled triangle using a star. Open a text editor for this tutorial I will be using vim editor. Create a c source file named rightAngledStar.c and open and write the following piece of code. Vim comes by default with the Unix Operating system. If you don't have vim text editor click [here](https://www.vim.org/) to download it.

```c
/*right angled star pattern */
#include <stdio.h>
int main(void) /*entry point of program*/
{
    int i, j;
    for (i = 1; i <= 5; i++) /*loop starts at 1 upto 5 */
    {
        for(j = 1; j < = i; j++)/*runs all its iterations for each iteration of outer loop*/ 
        {
            printf("*");/* print star pattern */
        }
        printf("\n");/*go to next line*/
    }
    return 0;
}
```

After you have written the above code save your code by pressing ctrl+x. Use GNU Compiler Collection compiler to run it. It is a best practice to include additional flags with running gcc command. To enforce the strictness and make your code robust. I will cover that in a brief.

```c
gcc -Wall -pedantic -Werror -wExtra -std=gnu89 rightAngledStar.c -o star
```

Explanation;

line 1: Multicomment style .The compiler usually ignores this piece of code.It explain the purpose of code.

line 2: header file which has the implementation of printf function.Used for printing output to screen.

line 4: declaration of variables to hold values.

```c
int i, j;
for (i=1;i<=5;i++)
{
    for (j=1;j<=i;j++)
    {
        printf("*");
    /* inner loop starts from 1 upto the count number of times 
the outer loop will run which is i.
It prints output then inner count variable j increments 
until it finishes all iterations then execution goes back again
to the outer loop for the next iteration of outer loop*/
    }
    printf("\n");
}
```

To put it simply the code is like a clock that increases from digit 1 upto digit 12.

Additional flags in a brief;

\-Wall: directs the compiler to give warning messages such as unused variables.

\-pedantic: tells the compiler to strictly follow the language standard defined in gcc compiler by default.

\-Werror: tells the compiler to treat all warnings as errors.

\-wExtra: makes the compiler give you even more warning than the usual ones you signed up for.

\-std=89: Tells the compiler to focus on adhering to gnu89 language rules.

Thanks for reading. See you in the next tutorial.