Computer Programming Strings – Definition, Examples & String Operations

A string is a sequence of characters grouped together to represent text. Strings are used to store names, messages, words, sentences, and any form of textual data.

Example:

"Hello"
"Welcome to Programming"

Strings are one of the most widely used data types in computer programming.

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What Is a String?

A string is a collection of characters enclosed within quotes.

• In C → strings use double quotes
• In Java → strings are objects of the String class
• In Python → strings are immutable sequences of Unicode characters

Example Values:

"John"
"12345"
"Hello World!"

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Strings in Different Programming Languages

programming strings, what is a string, C strings, Java string class, Python strings, string operations, string concatenation, substring, string manipulation, immutable strings

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Strings in C

In C, strings are stored as arrays of characters, ending with a special character ‘’ (null terminator).

Declaration

char name[10];

Initialization

char name[] = "John";

Accessing Characters

printf("%c", name[0]);  // Output: J

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Strings in Java

Java treats strings as objects of the built-in String class.

Declaration & Initialization

String name = "John";

Accessing Characters

System.out.println(name.charAt(0)); // Output: J

Useful Methods

name.length();
name.toUpperCase();
name.toLowerCase();
name.contains("oh");

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Strings in Python

Python strings are immutable and very flexible.

Declaration

name = "John"

Accessing Characters

print(name[0])  # Output: J

Useful Methods

name.upper()
name.lower()
name.replace("J", "K")
len(name)

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String Operations

1. Concatenation

Join two or more strings together.

C Example

strcat(str1, str2);

Java Example

String full = str1 + str2;

Python Example

full = str1 + str2

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2. Length of a String

C

strlen(name);

Java

name.length();

Python

len(name)

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3. Substrings

Extract part of a string.

Java

name.substring(1, 3);

Python

name[1:3]

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4. Comparing Strings

Java

name.equals("John");

Python

name == "John"

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Immutable vs Mutable Strings

Immutable Strings

Once created, cannot be changed.

• Java String
• Python str

Mutable Strings

Can be modified.

• C character arrays
• Java StringBuilder / StringBuffer

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String Applications

Strings play a vital role in:

• User input handling
• Data processing
• Text parsing
• File operations
• Web development
• Communication between systems
• Database queries

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FAQ

What is a string in programming?

A string is a sequence of characters used to represent text.

Are strings mutable?

In C, character arrays are mutable.
In Java and Python, strings are immutable.

How do I find the length of a string?

Use strlen() in C, .length() in Java, and len() in Python.

How do I combine two strings?

You can concatenate using + in Java and Python.
In C, use strcat().

Can strings contain numbers?

Yes, as long as they are enclosed in quotes.

# Summary

Here is what you've learned in this lesson:

• Computer Programming Strings – Definition, Examples & String Operations
• What Is a String?
• Strings in Different Programming Languages
• Strings in C
• Strings in Java
• Strings in Python
• String Operations
• Immutable vs Mutable Strings
• String Applications
• FAQ