Triangle Pattern Printing in C (Beginner Friendly)

🧠 Why Pattern Printing?

Pattern problems are a great way to:

• Practice nested loops
• Improve your logic and dry-run skills
• Prepare for coding interviews

In this guide, we’ll cover all the basic and common triangle patterns using simple C language code.

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📌 Pattern 1: Left-Aligned Right-Angled Triangle

Output:

pattern
1*
2**
3***
4****
5*****

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 1; i <= 5; i++) {
5        for(int j = 1; j <= i; j++) {
6            printf("*");
7        }
8        printf("\n");
9    }
10    return 0;
11}

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📌 Pattern 2: Right-Aligned Triangle

Output:

pattern
1    *
2   **
3  ***
4 ****
5*****

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 1; i <= 5; i++) {
5        for(int j = 1; j <= 5 - i; j++) {
6            printf(" ");
7        }
8        for(int k = 1; k <= i; k++) {
9            printf("*");
10        }
11        printf("\n");
12    }
13    return 0;
14}

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📌 Pattern 3: Inverted Left-Aligned Triangle

Output:

pattern
1*****
2****
3***
4**
5*

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 5; i >= 1; i--) {
5        for(int j = 1; j <= i; j++) {
6            printf("*");
7        }
8        printf("\n");
9    }
10    return 0;
11}

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📌 Pattern 4: Inverted Right-Aligned Triangle

Output:

pattern
1*****
2 ****
3  ***
4   **
5    *

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 5; i >= 1; i--) {
5        for(int j = 1; j <= 5 - i; j++) {
6            printf(" ");
7        }
8        for(int k = 1; k <= i; k++) {
9            printf("*");
10        }
11        printf("\n");
12    }
13    return 0;
14}

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📌 Pattern 5: Full Pyramid

Output:

pattern
1    *
2   ***
3  *****
4 *******
5*********

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 1; i <= 5; i++) {
5        for(int j = 1; j <= 5 - i; j++) {
6            printf(" ");
7        }
8        for(int k = 1; k <= 2 * i - 1; k++) {
9            printf("*");
10        }
11        printf("\n");
12    }
13    return 0;
14}

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📌 Pattern 6: Inverted Full Pyramid

Output:

pattern
1*********
2 *******
3  *****
4   ***
5    *

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 5; i >= 1; i--) {
5        for(int j = 1; j <= 5 - i; j++) {
6            printf(" ");
7        }
8        for(int k = 1; k <= 2 * i - 1; k++) {
9            printf("*");
10        }
11        printf("\n");
12    }
13    return 0;
14}

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📌 Pattern 7: Number Triangle

Output:

pattern
11
212
3123
41234
512345

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 1; i <= 5; i++) {
5        for(int j = 1; j <= i; j++) {
6            printf("%d", j);
7        }
8        printf("\n");
9    }
10    return 0;
11}

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📌 Pattern 8: Row Number Repeated

Output:

pattern
11
222
3333
44444
555555

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 1; i <= 5; i++) {
5        for(int j = 1; j <= i; j++) {
6            printf("%d", i);
7        }
8        printf("\n");
9    }
10    return 0;
11}

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📌 Pattern 9: Inverted Number Triangle

Output:

pattern
112345
21234
3123
412
51

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 5; i >= 1; i--) {
5        for(int j = 1; j <= i; j++) {
6            printf("%d", j);
7        }
8        printf("\n");
9    }
10    return 0;
11}

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📌 Pattern 10: Right-Aligned Number Triangle

Output:

pattern
1    1
2   12
3  123
4 1234
512345

c
1#include <stdio.h>
2
3int main() {
4    for(int i = 1; i <= 5; i++) {
5        for(int j = 1; j <= 5 - i; j++) {
6            printf(" ");
7        }
8        for(int k = 1; k <= i; k++) {
9            printf("%d", k);
10        }
11        printf("\n");
12    }
13    return 0;
14}

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🚀 DO THIS YOURSELF: Practice Challenge

Try printing the following pattern on your own:

pattern
1    1
2   2 2
3  3 3 3
4 4 4 4 4
55 5 5 5 5

💡 Hints:

• You need to handle both spaces and numbers
• Each number is followed by a space: use printf("%d ", i);
• Spaces = rows - i

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🎯

Pattern questions build your logic muscle. Once you're confident with these, try:

• Alphabet patterns
• Hollow pyramids
• Diamond shapes

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