String Visualizer

Learn string indexing, traversal, searching, slicing, and transformations with interactive controls and step-by-step animated explanations.

Current status: Ready with a 10-character string.

Use one character for editing and counting, or a longer value for search and concatenation.

Choose a position from 0 to 9 when the operation needs one.

Balanced

Character memory strip

Index → character → Unicode

current pointermatched range
d
Index 0: 'd' · U+0064
[0]U+0064start
B
Index 1: 'B' · U+0042
[1]U+0042
i
Index 2: 'i' · U+0069
[2]U+0069
X
Index 3: 'X' · U+0058
[3]U+0058
x
Index 4: 'x' · U+0078
[4]U+0078
a
Index 5: 'a' · U+0061
[5]U+0061
C
Index 6: 'C' · U+0043
[6]U+0043
D
Index 7: 'D' · U+0044
[7]U+0044
x
Index 8: 'x' · U+0078
[8]U+0078
G
Index 9: 'G' · U+0047
[9]U+0047end
"dBiXxaCDxG"10 UTF-16 code units

String Data Structure

A String is a sequence of characters used to represent text. In computer science, strings are typically implemented as arrays of characters. Depending on the programming language, strings can be either mutable (changeable) or immutable (unchangeable).

Time Complexity

  • Access (by Index)O(1)
  • Search (Linear)O(n)
  • ConcatenationO(n + m)
  • Insert/Delete (middle)O(n)

Immutability Explained

  • Java / Python: Strings are immutable. Any modification (like appending a character) actually creates a completely new string in memory, which can be costly (O(n)).
  • C++ (std::string): Strings are mutable. You can modify characters in place, similar to an array, often resulting in better performance for heavy manipulation.

Concept guide

Review the mental model, tradeoffs, and practical use cases after you experiment.

String Complete Info Card

ImmutableCharacter Sequence

Strings are immutable sequences of characters used to represent text. In most languages, any string operation that appears to modify the string actually creates a new string.

Time Complexities

Access by Index

Direct character access

O(1)

Concatenation

Creating new string from two strings

O(n + m)

Substring

Extracting portion of length k

O(k)

Length

Pre-stored length in most languages

O(1)

Search (Brute Force)

Finding substring in string

O(n*m)

Search (KMP Algorithm)

Optimized substring search

O(n + m)

Comparison

Lexicographical ordering

O(min(n,m))

Immutable Operations

Creates new string for modifications

O(n)

Common Operations

toUpperCase/toLowerCase

str.toUpperCase()

trim

str.trim()

split

str.split(",")

join

arr.join(" ")

Array method but string-related

replace

str.replace("old", "new")

charAt

str.charAt(3)

Character Encodings

ASCII

Range: 0-127

7-bit, English characters

UTF-8

Range: 1-4 bytes

Variable-width, supports all Unicode

UTF-16

Range: 2-4 bytes

Fixed/variable width

Latin-1

Range: 0-255

ISO-8859-1, Western European

Advantages

  • •Simple and intuitive text manipulation
  • •Thread-safe due to immutability
  • •Unicode support in modern languages

Limitations

  • •Memory overhead from immutability
  • •Encoding complexities with special characters
  • •Performance costs for frequent modifications
Pro Tip: Use StringBuilder/StringBuffer classes (in Java/C#) or join operations for efficient string concatenation in loops.
ImmutableUnicodeO(1) access