Left-Aligned Descending Number Triangle in C

What You’ll Learn

The left-aligned descending number triangle prints 54321, 5432, 543, 54, 5 — a natural step after Program 3’s reverse descending triangle. This tutorial covers ascending outer loop with shrinking inner bound, a live preview, algorithm steps, worked C examples, edge cases, and complexity.

📝 Problem & Approach

Given a positive integer rows (e.g. 5), print a left-aligned descending triangle: each row prints digits from rows down to i, with the outer loop counting from 1 up to rows.

// rows = 5
//54321
//5432
//543
//54
//5

Inputs & Outputs

Minimal workflow

for i from 1 to rows:
    for j from rows down to i:
        print j
    print newline

Approach comparison

🔮 Live Preview

Choose a row count between 3 and 9 and draw the left-aligned descending triangle in the browser.

Press "Draw pattern".

Examples Gallery

Three complete C programs — fixed rows, user input, and spaced output. Click View Output to reveal sample console results.

#include <stdio.h>

int main() {
    int rows = 5;
    int i, j;

    for (i = 1; i <= rows; i++) {
        for (j = rows; j >= i; j--)
            printf("%d", j);

        printf("\n");
    }

    return 0;
}

54321
5432
543
54
5

#include <stdio.h>

int main() {
    int rows;
    int i, j;

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

    for (i = 1; i <= rows; i++) {
        for (j = rows; j >= i; j--)
            printf("%d", j);

        printf("\n");
    }

    return 0;
}

Enter the number of rows: 4
4321
432
43
4

#include <stdio.h>

int main() {
    int rows = 5;
    int i, j;

    for (i = 1; i <= rows; i++) {
        for (j = rows; j >= i; j--)
            printf("%d ", j);

        printf("\n");
    }

    return 0;
}

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

🔎 Worked Walkthrough — rows = 5

Trace each outer-loop value of i, the inner-loop range, digit count, and full row output.

Prints per row = rows - i + 1 — total prints = n(n+1)/2 for n rows.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

💡 Best Practices