Why does this pattern use two main loops?

The first loop prints the upper half (i = 1..rows). The second loop prints the lower half (i = rows-1..1) to mirror the top without repeating the center row.

How does the program print the two diagonals?

The left diagonal prints when i == j. The right diagonal prints when i == k. All other positions print spaces.

Why does the lower half start from rows - 1?

To avoid duplicating the center row (the widest point of the X), which is already printed in the upper half.

What is the time complexity?

O(n^2), since we print a grid-like pattern using nested loops.

Complete X-Shaped Number Pattern in C

Beginner

⏱️ 6 min read

📚 Updated: Aug 2025

🎯 2 Code Examples

Conditions + Loops

Complete X-shaped number pattern output in C programming

What You’ll Learn

How to print a complete X-shaped pattern using two diagonals: one from top-left to bottom-right and another from top-right to bottom-left.

⭐ Pattern Output

For rows = 5, the pattern looks like this:

Output

Complete C Program

Print the upper half, then mirror it for the lower half. Two inner loops print the two diagonals.

#include <stdio.h>

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

    for (i = 1; i <= 5; i++) {
        for (j = 1; j <= 5; j++) {
            if (i == j)
                printf("%d", j);
            else
                printf(" ");
        }
        for (k = 4; k >= 1; k--) {
            if (i == k)
                printf("%d", k);
            else
                printf(" ");
        }
        printf("\n");
    }

    for (i = 4; i >= 1; i--) {
        for (j = 1; j <= 5; j++) {
            if (i == j)
                printf("%d", j);
            else
                printf(" ");
        }
        for (k = 4; k >= 1; k--) {
            if (i == k)
                printf("%d", k);
            else
                printf(" ");
        }
        printf("\n");
    }

    return 0;
}

Variation — User Input Version

Read the center size (rows) and build the same two-half logic.

#include <stdio.h>

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

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

    for (i = 1; i <= rows; i++) {
        for (j = 1; j <= rows; j++) {
            if (i == j)
                printf("%d", j);
            else
                printf(" ");
        }
        for (k = rows - 1; k >= 1; k--) {
            if (i == k)
                printf("%d", k);
            else
                printf(" ");
        }
        printf("\n");
    }

    for (i = rows - 1; i >= 1; i--) {
        for (j = 1; j <= rows; j++) {
            if (i == j)
                printf("%d", j);
            else
                printf(" ");
        }
        for (k = rows - 1; k >= 1; k--) {
            if (i == k)
                printf("%d", k);
            else
                printf(" ");
        }
        printf("\n");
    }

    return 0;
}