String Manipulation

String manipulation means inspecting and transforming text data. Strings are one of the most commonly used data types, and being able to work with them is essential for GCSE Computer Science (AQA 3.2 / OCR J277 2.2).

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What Is a String?

A string is a sequence of characters. Each character has a position (index), starting from 0:

Index	0	1	2	3	4	5	6	7	8	9	10	11
Char	H	e	l	l	o		W	o	r	l	d	!

greeting = "Hello World!"
print(greeting[0])   # H
print(greeting[6])   # W
print(greeting[11])  # !

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String Length

To find the number of characters in a string:

• Pseudocode: LEN("Hello") returns 5
• Python: len("Hello") returns 5

Note: Spaces, digits, and punctuation all count as characters.

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Substrings (Slicing)

A substring is a portion of a string. You extract substrings using slicing.

Pseudocode (AQA)