Strings in C++

Learn about strings in C++ programming, including C-style strings (character arrays) and the C++ string class, with examples and common operations.

Introduction

In C++, a string is a sequence of characters used to store and manipulate text. Strings are widely used in real-life applications, such as handling names, addresses, messages, and file operations.

C++ provides two ways to handle strings:

1. C-style strings (character arrays)
2. C++ string class (from <string> library)

Let’s explore both with real-world examples.

C-Style Strings (Character Arrays)

C-style strings are character arrays ending with a null character (\0).

Example:

#include <iostream>
using namespace std;

int main() {
    char name[] = "John"; // C-style string
    cout << "Hello, " << name << "!" << endl;
    return 0;
}

Explanation:

• char name[] = "John"; initializes a character array.
• The null character \0 is automatically added at the end.

Real-Life Analogy:

Think of a C-style string as a row of lockers where each locker stores a character:

J	o	h	n	\0

The \0 tells C++ where the string ends.

Limitation of C-Style Strings:

• Fixed size (cannot grow dynamically).
• Difficult to manipulate (no built-in functions for concatenation, searching, etc.).

C++ string Class (Modern Approach)

C++ provides the string class from the <string> library, which is more flexible and powerful.

Example:

#include <iostream>
#include <string>
using namespace std;

int main() {
    string name;
    cout << "Enter your name: ";
    cin >> name;
    cout << "Hello, " << name << "!" << endl;
    return 0;
}

Explanation:

• string name; declares a string variable.
• cin >> name; takes input (but stops at space).
• cout << name; prints the string.

Real-Life Analogy:

Imagine string as a dynamic notebook where you can write, erase, and modify text freely.

Key Differences

Feature	C-Style Strings (char[])	std::string (C++ Strings)
Null-Termination	Yes (\0 is required)	No (\0 is managed internally)
Memory Management	Manual (fixed size)	Dynamic (auto-resizes)
Safer?	❌ Prone to buffer overflows	✅ Safer and more convenient
Functionality	Limited (needs <cstring>)	Rich methods (length, find, substr, etc.)

🔹 Best Practice:
Always prefer std::string over C-style strings unless you have a specific reason to use character arrays (e.g., low-level memory manipulation, embedded systems).

Taking Full-Line Input (getline)

To handle multi-word input, use getline().

Example:

#include <iostream>
#include <string>
using namespace std;

int main() {
    string fullName;
    cout << "Enter your full name: ";
    getline(cin, fullName);
    cout << "Hello, " << fullName << "!" << endl;
    return 0;
}

Why getline()?

cin only takes a single word, but getline(cin, variable); reads the whole line, including spaces.

String Operations

Concatenation (Joining Strings)

#include <iostream>
#include <string>
using namespace std;

int main() {
    string firstName = "John";
    string lastName = "Doe";
    string fullName = firstName + " " + lastName;
    cout << "Full Name: " << fullName << endl;
    return 0;
}

Explanation:

• + operator joins strings.
• " " adds a space between first and last names.

Finding String Length

string str = "Hello";
cout << "Length: " << str.length() << endl; // Output: 5

Accessing Characters

cout << str[0]; // First character (H)

Modifying Strings

str[0] = 'h'; // Changes "Hello" to "hello"

Common Errors and Solutions

Error	Cause	Solution
cin skips input	getline() follows cin	Use cin.ignore() before getline()
String out of bounds	Accessing invalid index	Ensure index is within 0 to str.length()-1
Concatenation error	Using + with char[]	Use string class instead of char[]

Conclusion

• C-style strings are character arrays with \0 termination.
• C++ string class is modern and easy to use.
• getline() handles multi-word input.
• String operations include concatenation, length, access, and modification.

In the next article, we’ll explore Mathematical Functions in C++ to perform numerical operations efficiently.