C Academy · Lesson

Bitwise Operators

AND, OR, XOR, NOT.

Bitwise Operators is a free C Academy lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Working at the Bit Level

Integers are stored as sequences of bits. C lets you operate on those bits directly with the bitwise operators.

The four core operators are AND &, OR |, XOR ^, and NOT ~.

#include <stdio.h>

int main(void) {
    unsigned a = 12;
    unsigned b = 10;
    printf("a & b = %u\n", a & b);
    return 0;
}

Bitwise AND

The & operator sets a result bit to 1 only when both input bits are 1.

For 12 (1100) and 10 (1010), the result is 8 (1000).

#include <stdio.h>

int main(void) {
    unsigned a = 12, b = 10;
    printf("%u & %u = %u\n", a, b, a & b);
    return 0;
}

Bitwise OR

The | operator sets a result bit to 1 when at least one input bit is 1.

12 (1100) OR 10 (1010) is 14 (1110).

#include <stdio.h>

int main(void) {
    unsigned a = 12, b = 10;
    printf("%u | %u = %u\n", a, b, a | b);
    return 0;
}

Bitwise XOR

The ^ operator (exclusive OR) sets a result bit to 1 when the input bits differ.

12 (1100) XOR 10 (1010) is 6 (0110).

#include <stdio.h>

int main(void) {
    unsigned a = 12, b = 10;
    printf("%u ^ %u = %u\n", a, b, a ^ b);
    return 0;
}

Bitwise NOT

The ~ operator flips every bit. On unsigned values, ~0 is all ones, the maximum value.

#include <stdio.h>

int main(void) {
    unsigned char x = 0;
    printf("~0 as 8-bit = %u\n", (unsigned char)~x);
    return 0;
}

Printing Bits

A helper that prints the binary form of a byte makes bitwise results easier to understand. We test each bit from high to low.

#include <stdio.h>

void print_bits(unsigned char v) {
    for (int i = 7; i >= 0; i--) {
        putchar((v >> i) & 1 ? '1' : '0');
    }
    putchar('\n');
}

int main(void) {
    print_bits(12);
    print_bits(10);
    return 0;
}

XOR Swap

XOR has a neat property: you can swap two integers without a temporary variable.

Apply XOR three times to exchange the values.

#include <stdio.h>

int main(void) {
    int a = 5, b = 9;
    a = a ^ b;
    b = a ^ b;
    a = a ^ b;
    printf("a=%d b=%d\n", a, b);
    return 0;
}

XOR with Itself

Any value XORed with itself is 0, and any value XORed with 0 is unchanged.

These identities power the XOR swap and many tricks.

#include <stdio.h>

int main(void) {
    int x = 42;
    printf("x ^ x = %d\n", x ^ x);
    printf("x ^ 0 = %d\n", x ^ 0);
    return 0;
}

Bitwise vs Logical

Do not confuse & with && or | with ||.

Bitwise operators work on every bit of the operands.
Logical operators evaluate truthiness and return 0 or 1.

#include <stdio.h>

int main(void) {
    printf("2 & 1 = %d\n", 2 & 1);
    printf("2 && 1 = %d\n", 2 && 1);
    return 0;
}

Combining Operators

Bitwise operators combine to express complex conditions. Here we keep bits that are in a but not in b.

#include <stdio.h>

int main(void) {
    unsigned a = 0b1111;
    unsigned b = 0b0101;
    unsigned only_a = a & ~b;
    printf("only_a = %u\n", only_a);
    return 0;
}

Checking Parity with XOR

XORing all bits together tells you the parity (whether the number of set bits is odd). Fold the value down repeatedly.

#include <stdio.h>

int main(void) {
    unsigned v = 0b1011;
    int parity = 0;
    while (v) {
        parity ^= (v & 1);
        v >>= 1;
    }
    printf("parity = %d\n", parity);
    return 0;
}

Quick Check

Test your knowledge of bitwise operators.

Recap

You learned the bitwise operators:

& AND keeps bits set in both operands.
| OR keeps bits set in either operand.
^ XOR keeps bits that differ.
~ NOT flips all bits.
Bitwise differs from logical && and ||.

Frequently asked questions

Is the “Bitwise Operators” lesson free?

Yes — the full text of “Bitwise Operators” is free to read here on the web, and the C Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C Academy course, upgrade to CoddyKit PRO.

What will I learn in “Bitwise Operators”?

AND, OR, XOR, NOT. You practise C Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C Academy?

No prior experience is required. C Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Bitwise Operators” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C Academy lesson?

Yes. Every C Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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