C Program that receives a number and prints it out in large size

In C, we can create a program that displays numbers in large size using ASCII art patterns made with hash symbols. This technique is useful for creating visually appealing banner-style output or digital displays.

Syntax

void printLargeNumber(char number[]);

Approach

The solution uses predefined character arrays to store ASCII art patterns for each digit (0-9). Each digit pattern is 7 rows high and 8 characters wide −

• Define 2D character arrays for each digit's visual pattern
• Traverse the input string character by character
• Print corresponding patterns row by row to display digits side by side

Example

Here's a complete program that prints numbers in large size using hash symbols −

#include <stdio.h>
#include <string.h>
#define H 7
#define W 8

void printLargeNumber(char num[]) {
    int i, j, k;
    
    /* Predefined patterns for each digit */
    char zero[H][W] = {" ##### ", " #   # ", " #   # ", " #   # ", " #   # ", " #   # ", " ##### "};
    char one[H][W] = {"   #   ", "  ##   ", "   #   ", "   #   ", "   #   ", "   #   ", " ##### "};
    char two[H][W] = {" ##### ", "     # ", "     # ", " ##### ", " #     ", " #     ", " ##### "};
    char three[H][W] = {" ##### ", "     # ", "     # ", " ##### ", "     # ", "     # ", " ##### "};
    char four[H][W] = {" #   # ", " #   # ", " #   # ", " ##### ", "     # ", "     # ", "     # "};
    char five[H][W] = {" ##### ", " #     ", " #     ", " ##### ", "     # ", "     # ", " ##### "};
    char six[H][W] = {" ##### ", " #     ", " #     ", " ##### ", " #   # ", " #   # ", " ##### "};
    char seven[H][W] = {" ##### ", "     # ", "     # ", "    #  ", "   #   ", "  #    ", " #     "};
    char eight[H][W] = {" ##### ", " #   # ", " #   # ", " ##### ", " #   # ", " #   # ", " ##### "};
    char nine[H][W] = {" ##### ", " #   # ", " #   # ", " ##### ", "     # ", "     # ", " ##### "};
    
    if (strlen(num) > 10) {
        printf("\nYou must enter a number up to 10 digits.<br>");
        return;
    }
    
    printf("<br>");
    
    /* Print each row of all digits */
    for (j = 0; j < H; j++) {
        for (i = 0; i < strlen(num); i++) {
            switch (num[i]) {
                case '0': printf("%s", zero[j]); break;
                case '1': printf("%s", one[j]); break;
                case '2': printf("%s", two[j]); break;
                case '3': printf("%s", three[j]); break;
                case '4': printf("%s", four[j]); break;
                case '5': printf("%s", five[j]); break;
                case '6': printf("%s", six[j]); break;
                case '7': printf("%s", seven[j]); break;
                case '8': printf("%s", eight[j]); break;
                case '9': printf("%s", nine[j]); break;
                default: printf("       "); break;
            }
        }
        printf("<br>");
    }
}

int main() {
    char number[] = "2168";
    printf("Large size representation of %s:", number);
    printLargeNumber(number);
    return 0;
}

Output

Large size representation of 2168:

 #####    #    #####  ##### 
     #   ##    #      #   # 
     #    #    #      #   # 
 #####    #    #####  ##### 
 #        #    #   #  #   # 
 #        #    #   #  #   # 
 #####  ##### #####  ##### 

How It Works

1. Pattern Definition: Each digit (0-9) is stored as a 7x8 character array with hash symbols forming the digit shape
2. Row-wise Printing: The outer loop iterates through each row (0 to 6), while the inner loop processes each character in the input string
3. Character Mapping: A switch statement maps each input character to its corresponding pattern array
4. Side-by-side Display: All digits are printed horizontally by processing the same row of each digit before moving to the next row

Key Points

• The program supports numbers up to 10 digits in length
• Each digit pattern is exactly 7 rows high and 8 characters wide for consistency
• Uses a switch statement for cleaner code compared to multiple if-else conditions
• The outer loop controls the row, inner loop controls the digit position

Conclusion

This C program effectively creates large ASCII art representations of numbers using predefined character patterns. It demonstrates practical use of 2D arrays and string manipulation for visual output formatting.