Bash Script to Convert Decimal to Hexadecimal

Use printf '%X\n' decimal_number in Bash to convert a decimal number to its hexadecimal representation.

Examples

Input10

OutputA

Input255

OutputFF

Input0

Output0

How to Think About It

To convert decimal to hexadecimal in Bash, think of the decimal number as a base-10 value that you want to express in base-16. Bash's built-in printf command can format numbers in hexadecimal using the %X format specifier, which automatically handles the conversion.

Algorithm

1

Get the decimal number input from the user or as an argument.

2

Use the <code>printf</code> command with the <code>%X</code> format specifier to convert the decimal number to hexadecimal.

3

Print the resulting hexadecimal value.

Code

bash

#!/bin/bash

# Read decimal number from input
read -p "Enter a decimal number: " decimal

# Convert to hexadecimal and print
printf '%X\n' "$decimal"

Output

Enter a decimal number: 255
FF

Dry Run

Let's trace converting decimal 255 to hexadecimal using the script.

1

Input decimal number

User enters 255

2

Run printf command

printf '%X\n' 255

3

Output hexadecimal

FF

Decimal Input	printf Command	Hexadecimal Output
255	printf '%X\n' 255	FF

Why This Works

Step 1: Using printf for formatting

The printf command formats output; %X tells it to convert the number to uppercase hexadecimal.

Step 2: Input as decimal

The input number is treated as decimal by default, so no extra conversion is needed before formatting.

Step 3: Output is hexadecimal

The result printed is the hexadecimal equivalent of the decimal input.

Alternative Approaches

Using bc command

bash

read -p "Enter decimal: " dec
hex=$(echo "obase=16; $dec" | bc)
echo "$hex"

This uses the bc calculator for conversion; it supports uppercase letters by default and works well for large numbers but requires bc installed.

Using printf with lowercase hex

bash

read -p "Enter decimal: " dec
printf '%x\n' "$dec"

This prints hexadecimal in lowercase letters instead of uppercase.

Complexity: O(1) time, O(1) space

Time Complexity

The conversion uses built-in formatting with no loops, so it runs in constant time.

Space Complexity

Only a few variables are used, so space usage is constant.

Which Approach is Fastest?

Using printf is fastest and simplest; bc is flexible but slower due to external process.

Approach	Time	Space	Best For
printf '%X'	O(1)	O(1)	Simple, fast conversion
bc command	O(1)	O(1)	Large numbers, uppercase hex, flexible
printf '%x'	O(1)	O(1)	Lowercase hex output