How to Retrieve Substring in Batch Script

The string is an array of characters, and the substring is a specific part of the string. Sometimes we need to retrieve substrings for various purposes like matching or finding specific substrings.

This article will tackle the string’s methods to get a substring.

Retrieve Substring From a String in Batch Script

We need to follow these general formats to retrieve specific characters from a string variable.

%VARIABLE:~START_INDEX%
or
%VARIABLE:~START_INDEX,END_INDEX%

The START_INDEX is a numeric value indicating the string’s starting point. You can use negative numbers, but a negative number will count backward from the ending point of the string.

The END_INDEX is a numeric value indicating the string’s ending point. You can use negative numbers, but a negative number will count backward from the ending point of the string.

Remember, the indexing starts from 0 and not 1.

In the following example, we will declare a string variable containing numeric and alphabetic characters. We’ll retrieve the numeric and alphabetic characters from the string as a substring.

Batch Script:

@echo off
SET testString=abcdefgh123456789
SET numericChars=%testString:~8,16%
SET normalChars=%testString:~0,7%
ECHO Numeric characters: %numericChars% Alphabetic characters: %normalChars%

In this 1st line code(SET testString=abcdefgh123456789), we declared a variable named testString and assigned it with numeric and alphabetic characters.

In this 2nd line code(SET numericChars=%testString:~8,16%), we retrieve the numeric character part of the string, which is 123456789, and assign the result to a variable named numericChars. The start index is 8, and the ending index is 16.

3rd line of code(SET normalChars=%testString:~0,7%), we retrieved the alphabetic character part of the string abcdefgh and assigned the result to a variable named normalChars. The start index is 0, and the ending index is 7.

We printed our results with this last code line (ECHO Numeric characters: %numericChars% Alphabetic characters: %normalChars%).

Output:

Numeric characters: 123456789 Alphabetic characters: abcdefg

Remember the example here are written using Batch Script and only work in a windows CMD environment.