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How to Convert Text to Binary in Batch Script

Converting a string of text into its binary representation (a sequence of 1s and 0s) is a foundational concept in computing. While not a common daily task, it can be useful for understanding data storage, for low-level data manipulation, or for educational purposes. Windows Batch, however, is a high-level shell and has no native, built-in commands to perform this complex conversion.

This guide will explain why a "pure-batch" approach is impractical and should be avoided. Instead, it will teach you the definitive, modern, and only recommended method: calling a powerful PowerShell one-liner from your batch script. You will learn how this command works to accurately convert any string into its binary equivalent.

The Challenge: Why Pure Batch is Not a Viable Solution​

Attempting to convert text to binary in pure batch is not just difficult; it's practically impossible to do in a reliable way. The process requires two main steps, both of which are missing from cmd.exe:

  1. Get the ASCII/Unicode value of a character: There is no native batch function to get the numerical value of a character (e.g., to find out that "A" is 65).
  2. Convert a decimal number to a binary string: While this is possible with a complex loop using the modulo operator, it's slow and cumbersome.

Any "pure-batch" script that attempts this is a multi-hundred-line monstrosity that is extremely slow and fragile. It is not a practical solution.

The correct and professional way to handle this is to call PowerShell, which has direct access to the .NET Framework's powerful data conversion tools.

This one-liner can be called directly from your batch script to perform the entire conversion.

powershell -Command "$text='%YourString%'; $bytes=[System.Text.Encoding]::ASCII.GetBytes($text); $binaryStrings=foreach($byte in $bytes){[Convert]::ToString($byte, 2).PadLeft(8,'0')}; $binaryStrings -join ' '"

This command is long but robust. We will break down how it works.

Basic Example: Converting "Hello" to Binary​

This script uses the PowerShell one-liner to convert the word "Hello".

@ECHO OFF
SET "MyString=Hello"
SET "BinaryResult="

ECHO --- Converting "%MyString%" to Binary ---
ECHO.

FOR /F "delims=" %%B IN (
    'powershell -Command "$text='%MyString%'; $bytes=[System.Text.Encoding]::ASCII.GetBytes($text); $binaryStrings=foreach($byte in $bytes){[Convert]::ToString($byte, 2).PadLeft(8,'0')}; $binaryStrings -join ' '"'
) DO (
    SET "BinaryResult=%%B"
)

ECHO The binary representation is:
ECHO %BinaryResult%

Output:

--- Converting "Hello" to Binary ---

The binary representation is:
01001000 01100101 01101100 01101100 01101111

How the PowerShell Method Works (A Step-by-Step Breakdown)​

Let's deconstruct the PowerShell command:

  1. $text='%MyString%';: It starts by assigning our batch variable's value to a PowerShell variable named $text.
  2. $bytes=[System.Text.Encoding]::ASCII.GetBytes($text);: This is the first key step. It takes the string and converts it into an array of its numerical byte values using the ASCII encoding standard. For "Hello", this produces the array [72, 101, 108, 108, 111].
  3. $binaryStrings=foreach($byte in $bytes){...};: This is a loop that runs for each number in the $bytes array.
  4. [Convert]::ToString($byte, 2): Inside the loop, this is the conversion command. It takes a byte (e.g., 72) and converts it to its string representation in base 2 (binary). For 72, this produces 1001000.
  5. .PadLeft(8,'0'): The result 1001000 is only 7 bits long. A full byte is 8 bits. This method pads the string on the left with zeros until it has a total width of 8 characters. The result is 01001000.
  6. $binaryStrings -join ' ': After the loop has finished, $binaryStrings is an array of all the 8-bit binary strings. The -join ' ' operator combines them into a single string, separated by spaces.

Common Pitfalls and How to Solve Them​

Problem: Character Encoding (ASCII vs. UTF-8)​

The example uses ASCII, which only works for standard English characters. If your string contains special characters like é or €, you will get incorrect results or question marks.

Solution: For strings that may contain international characters, you must change the encoding to UTF-8. ... [System.Text.Encoding]::UTF8.GetBytes($text) ... This is the more robust choice for handling unknown text.

Problem: Capturing the Output into a Variable​

The output from the PowerShell command is a simple string written to its standard output.

Solution: The FOR /F loop is the standard and correct way to capture this single line of output and assign it to a batch script variable, as shown in the examples.

Practical Example: An Interactive Text-to-Binary Converter​

This script prompts the user for text and uses the robust PowerShell method to display its binary representation.

@ECHO OFF
SETLOCAL

:Prompt
ECHO.
SET "InputText="
SET /P "InputText=Enter the text you want to convert (or type 'exit'): "

IF /I "%InputText%"=="exit" GOTO :EOF

SET "BinaryOutput="
REM --- Use the UTF8 version for better character support ---
FOR /F "delims=" %%B IN (
    'powershell -NoProfile -Command "$text='%InputText%'; $bytes=[System.Text.Encoding]::UTF8.GetBytes($text); $binaryStrings=foreach($byte in $bytes){[Convert]::ToString($byte, 2).PadLeft(8,'0')}; $binaryStrings -join ' '"'
) DO (
    SET "BinaryOutput=%%B"
)

ECHO.
ECHO Binary Result:
ECHO %BinaryOutput%
ECHO --------------------------------------------------
GOTO :Prompt

ENDLOCAL

Conclusion​

While converting text to binary is far beyond the native capabilities of batch scripting, it is a perfect example of how a batch file can act as a "launcher" for more powerful, modern tools.

Key takeaways:

  • Do not attempt to convert text to binary using a pure-batch script. The method is impractical and unreliable.
  • The PowerShell one-liner is the only correct and recommended solution. It is fast, accurate, and can handle all character encodings.
  • For international characters, use [System.Text.Encoding]::UTF8 instead of ASCII.
  • Use a standard FOR /F loop to capture the resulting binary string into a batch variable.

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