21_pattern_examples.md

Pattern Programs in C

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Pattern programs are commonly used to practice loops and understand control flow in C.
They help visualize how nested loops work and how output can be formatted.

1. Star Triangle Pattern

Code:

#include <stdio.h>

int main() {
    int rows = 5;
    // Outer loop for each row
    for (int i = 1; i <= rows; i++) {
        // Inner loop for printing stars in each row
        for (int j = 1; j <= i; j++) {
            printf("* ");
        }
        printf("\n"); // Move to next line after each row
    }
    return 0;
}

Explanation:

• The outer loop (i) controls the number of rows.
• The inner loop (j) prints stars equal to the current row number.
• After printing stars for a row, a newline is printed.

Output:

* 
* * 
* * * 
* * * * 
* * * * * 

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2. Number Pyramid Pattern

Code:

#include <stdio.h>

int main() {
    int rows = 5;
    for (int i = 1; i <= rows; i++) {
        // Print spaces for pyramid shape
        for (int s = 1; s <= rows - i; s++) {
            printf("  ");
        }
        // Print numbers
        for (int j = 1; j <= i; j++) {
            printf("%d ", j);
        }
        printf("\n");
    }
    return 0;
}

Explanation:

• Spaces are printed before numbers to create the pyramid shape.
• Numbers from 1 to the current row number are printed in each row.

Output:

        1 
      1 2 
    1 2 3 
  1 2 3 4 
1 2 3 4 5 

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3. Inverted Star Pattern

Code:

#include <stdio.h>

int main() {
    int rows = 5;
    for (int i = rows; i >= 1; i--) {
        for (int j = 1; j <= i; j++) {
            printf("* ");
        }
        printf("\n");
    }
    return 0;
}

Explanation:

• Starts with the maximum number of stars and decreases each row.

Output:

* * * * * 
* * * * 
* * * 
* * 
* 

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4. Centered Pyramid Star Pattern

Code:

#include <stdio.h>

int main() {
    int i, j;
    int n = 8;

    for (i = 1; i <= n; i++) {
        // Print spaces
        for (j = 1; j <= n - i; j++) {
            printf(" ");
        }
        // Print stars
        for (j = 1; j <= 2 * i - 1; j++) {
            printf("*");
        }
        printf("\n");
    }
    return 0;
}

Explanation:

• Prints spaces to center the stars.
• Prints an odd number of stars in each row to form a pyramid.

Output:

       *
      ***
     *****
    *******
   *********
  ***********
 *************
***************

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5. Increasing Number Triangle

Code:

#include <stdio.h>

int main() {
    int i, j;
    for (i = 1; i <= 5; i++) {
        printf("\n");
        for (j = 1; j <= i; j++) {
            printf("%d", j);
        }
    }
    return 0;
}

Explanation:

• Each row prints numbers from 1 up to the current row number.

Output:

1
12
123
1234
12345

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6. Decreasing Number Triangle

Code:

#include <stdio.h>

int main() {
    int i, j;
    for (i = 5; i >= 1; i--) {
        printf("\n");
        for (j = 5; j >= i; j--) {
            printf("%d", j);
        }
    }
    return 0;
}

Explanation:

• Each row prints numbers starting from 5 down to the current row number.

Output:

5
54
543
5432
54321

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7. Solid Square Star Pattern

Code:

#include <stdio.h>

int main() {
    for (int i = 1; i <= 4; i++) {
        for (int j = 1; j <= 4; j++) {
            printf("*");
        }
        printf("\n");
    }
    return 0;
}

Explanation:

• Prints a solid square of stars with 4 rows and 4 columns.

Output:

****
****
****
****

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Summary

• Pattern programs use nested loops for rows and columns.
• They are useful for practicing logic, loops, and output formatting in C.
• Try modifying the code to create your own patterns!

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