Introduction to Programming in C

📘 Bitwise Operators and Bit Manipulation in C

Bitwise operators in C allow you to work directly with individual bits of integer data types. This is extremely useful in systems programming, embedded systems, hardware control, and performance-optimized code.

🔹 What is a Bit?

A bit is the smallest unit of data in computing. It can hold a value of either 0 or 1. All data in memory is ultimately stored and manipulated as bits.

🔹 Bitwise Operators in C

🔧 Examples

int a = 5;   // 0101 in binary
int b = 3;   // 0011 in binary

printf("a & b = %d\n", a & b);   // 0001 = 1
printf("a | b = %d\n", a | b);   // 0111 = 7
printf("a ^ b = %d\n", a ^ b);   // 0110 = 6
printf("~a = %d\n", ~a);         // Bitwise NOT of a (compiler dependent)
printf("a << 1 = %d\n", a << 1); // 1010 = 10
printf("a >> 1 = %d\n", a >> 1); // 0010 = 2

📚 UdaanPath Example: Permission System

Suppose you are storing user permissions (Read, Write, Execute) as bits:

#define READ  0x1  // 0001
#define WRITE 0x2  // 0010
#define EXEC  0x4  // 0100

int userPerms = READ | WRITE; // 0011

// Check if user has EXEC permission
if (userPerms & EXEC) {
    printf("User can execute\n");
} else {
    printf("User cannot execute\n");
}

🧠 Why Bitwise Operations Matter?

• Used in compression, encryption, image processing.
• Improve performance in low-level hardware access.
• Efficient data flags and status representation.

🛠 Bit Masks

Bit masks are patterns used to set, clear, or toggle specific bits.

// Set 2nd bit
x = x | (1 << 1);

// Clear 2nd bit
x = x & ~(1 << 1);

// Toggle 2nd bit
x = x ^ (1 << 1);

📝 Practice Tasks

1. Write a program to swap two numbers using bitwise XOR.
2. Check if a number is even or odd using bitwise AND.
3. Write a function to count number of 1s in the binary representation of a number.
4. Implement a toggle permission system using bit masks.

✅ Summary

• Bitwise operators perform operations at the bit level.
• Useful for performance-sensitive, low-level programming.
• Bit masking is a technique for flag manipulation.

🚀 Coming Next

Next, we’ll explore Header Files and Modular Programming — organizing your C code for reuse and maintainability.