Substring

Extracts a portion of a string starting at a specified position.

Syntax

Substring(text, start)
Substring(text, start, length)

Parameters

• text (string): The source string to extract from
• start (number): The zero-based starting position (must be integer)
• length (number, optional): The number of characters to extract. If omitted, extracts to the end of the string

Returns

• string: The extracted substring

Description

Extracts a portion of a string starting at the specified position. If a length is provided, extracts that many characters; otherwise extracts from the start position to the end of the string.

Handles edge cases gracefully:

• Negative start indices are treated as 0
• Start positions beyond the string length return an empty string
• Length values that would exceed the string are automatically clamped
• Zero or negative length values return an empty string

Examples

Basic extraction

var result = Substring("Hello World", 0, 5)  # Returns "Hello"

Extract to end of string

var result = Substring("Hello World", 6)  # Returns "World"

Extract middle portion

var email = "user@example.com"
var domain = Substring(email, 5)  # Returns "example.com"

With calculated positions

var filename = "document.pdf"
var extension = Substring(filename, 9, 3)  # Returns "pdf"

Edge case handling

var result1 = Substring("Hello", 10)     # Returns "" (start beyond length)
var result2 = Substring("Hello", 0, 100) # Returns "Hello" (length clamped)
var result3 = Substring("Hello", -5, 3)  # Returns "Hel" (negative start treated as 0)

Notes

• Uses zero-based indexing (first character is at position 0)
• The function never throws for out-of-bounds values; it returns empty string or clamped results
• For finding the position of a substring, use PositionOf