Bitmasks and Bit Manipulation

?Why Do We Need Bitmasks?

Imagine storing 8 yes/no settings. You could use 8 bool variables (8 bytes), or use 1 byte with bitmasks. Bitmasks are essential for:

File Permissions

chmod 755 uses octal bitmasks:

rwx = 111 = 7 (Owner)
r-x = 101 = 5 (Group)
r-x = 101 = 5 (Others)

Game Development

Store player states, power-ups, collision layers — all in compact bit flags.

Hardware & Embedded

Control registers in microcontrollers are all bit fields.

Network Protocols

TCP/IP headers pack multiple flags into single bytes.

Memory savings: Storing 32 boolean flags takes 32 bytes with bool, but only 4 bytes with bitmasks — 8× more efficient!

01What are Bitmasks?

• Simple Definition

A bitmask is a pattern of bits used to manipulate individual bits within a number. Each bit acts as an ON/OFF flag!

Key Benefits

Memory Efficient

Store 8 flags in 1 byte!

Fast Operations

Bitwise ops are very fast

Permissions

Read, Write, Execute flags

Hardware Control

Control device registers

02Bitwise Operators Review

Operator	Name	Description	Example
&	AND	1 if both bits are 1	5 & 3 = 1
\|	OR	1 if either bit is 1	5 \| 3 = 7
^	XOR	1 if bits are different	5 ^ 3 = 6
~	NOT	Flip all bits	~5 = -6
<<	Left Shift	Shift bits left	5 << 1 = 10
>>	Right Shift	Shift bits right	5 >> 1 = 2

03Understanding Binary: Visual Guide

# 8-bit Number Visualization

Each bit position has a power-of-2 value. To get the decimal value, add up where bits are 1.

bit 7

bit 6

bit 5

bit 4

bit 3

bit 2

bit 1

bit 0

128

Example: 13 in binary

8 + 4 + 1 = 13

04Common Bitmask Operations

Visual: Set Bit 2 of value 9

Value: 9 = 0000 1001

Mask: 1 << 2 = 0000 0100

| (OR)

Result: 13 = 0000 1101

Operation	Code	Description
Set bit	x \| (1 << n)	Turn bit n ON (use OR with mask)
Clear bit	x & ~(1 << n)	Turn bit n OFF (AND with inverted mask)
Toggle bit	x ^ (1 << n)	Flip bit n (XOR toggles)
Check bit	(x >> n) & 1	Is bit n set? (returns 0 or 1)

bitmask_operations.c

1#include <stdio.h>
2
3// Helper function to print binary
4void printBinary(unsigned int n, int bits) {
5    for (int i = bits - 1; i >= 0; i--) {
6        printf("%d", (n >> i) & 1);
7    }
8}
9
10int main() {
11    unsigned int x = 0b00001010;  // Start with 10
12    
13    printf("Original:    ");
14    printBinary(x, 8);
15    printf(" = %d\n", x);
16    
17    // SET bit 0 (rightmost)
18    x = x | (1 << 0);
19    printf("Set bit 0:   ");
20    printBinary(x, 8);
21    printf(" = %d\n", x);
22    
23    // SET bit 4
24    x = x | (1 << 4);
25    printf("Set bit 4:   ");
26    printBinary(x, 8);
27    printf(" = %d\n", x);
28    
29    // CLEAR bit 1
30    x = x & ~(1 << 1);
31    printf("Clear bit 1: ");
32    printBinary(x, 8);
33    printf(" = %d\n", x);
34    
35    // TOGGLE bit 3
36    x = x ^ (1 << 3);
37    printf("Toggle bit 3:");
38    printBinary(x, 8);
39    printf(" = %d\n", x);
40    
41    // CHECK if bit 4 is set
42    if ((x >> 4) & 1) {
43        printf("Bit 4 is SET\n");
44    } else {
45        printf("Bit 4 is NOT set\n");
46    }
47    
48    return 0;
49}

Output

Original: 00001010 = 10

Set bit 0: 00001011 = 11

Set bit 4: 00011011 = 27

Clear bit 1: 00011001 = 25

Toggle bit 3:00010001 = 17

Bit 4 is SET

04Practical Example: File Permissions

permissions.c

1#include <stdio.h>
2
3// Define permission flags using bit positions
4#define READ    (1 << 0)  // 001 = 1
5#define WRITE   (1 << 1)  // 010 = 2
6#define EXECUTE (1 << 2)  // 100 = 4
7
8void printPermissions(int perms) {
9    printf("Permissions: ");
10    if (perms & READ)    printf("Read ");
11    if (perms & WRITE)   printf("Write ");
12    if (perms & EXECUTE) printf("Execute ");
13    printf("\n");
14}
15
16int main() {
17    int permissions = 0;  // No permissions
18    
19    printf("=== File Permission System ===\n\n");
20    
21    // Grant READ permission
22    permissions |= READ;
23    printf("After granting READ:\n");
24    printPermissions(permissions);
25    
26    // Grant WRITE permission
27    permissions |= WRITE;
28    printf("After granting WRITE:\n");
29    printPermissions(permissions);
30    
31    // Grant EXECUTE permission
32    permissions |= EXECUTE;
33    printf("After granting EXECUTE:\n");
34    printPermissions(permissions);
35    
36    // Revoke WRITE permission
37    permissions &= ~WRITE;
38    printf("After revoking WRITE:\n");
39    printPermissions(permissions);
40    
41    // Check specific permission
42    if (permissions & EXECUTE) {
43        printf("\nUser CAN execute this file.\n");
44    }
45    
46    if (!(permissions & WRITE)) {
47        printf("User CANNOT write to this file.\n");
48    }
49    
50    // Grant multiple at once
51    int fullAccess = READ | WRITE | EXECUTE;
52    printf("\nFull access value: %d (binary: ", fullAccess);
53    for (int i = 2; i >= 0; i--) printf("%d", (fullAccess >> i) & 1);
54    printf(")\n");
55    
56    return 0;
57}

Output

=== File Permission System ===

After granting READ:

Permissions: Read

After granting WRITE:

Permissions: Read Write

After granting EXECUTE:

Permissions: Read Write Execute

After revoking WRITE:

Permissions: Read Execute

User CAN execute this file.

User CANNOT write to this file.

Full access value: 7 (binary: 111)

05Practical Example: Game Flags

game_flags.c

1#include <stdio.h>
2
3// Game state flags
4#define HAS_SWORD      (1 << 0)  // 0001
5#define HAS_SHIELD     (1 << 1)  // 0010
6#define HAS_POTION     (1 << 2)  // 0100
7#define QUEST_COMPLETE (1 << 3)  // 1000
8
9void printInventory(int flags) {
10    printf("Inventory: ");
11    if (flags & HAS_SWORD)      printf("[Sword] ");
12    if (flags & HAS_SHIELD)     printf("[Shield] ");
13    if (flags & HAS_POTION)     printf("[Potion] ");
14    if (flags & QUEST_COMPLETE) printf("[Quest✓] ");
15    if (flags == 0)             printf("[Empty]");
16    printf("\n");
17}
18
19int main() {
20    int playerFlags = 0;
21    
22    printf("=== Adventure Game ===\n\n");
23    printInventory(playerFlags);
24    
25    // Pick up sword
26    printf("You found a SWORD!\n");
27    playerFlags |= HAS_SWORD;
28    printInventory(playerFlags);
29    
30    // Pick up shield
31    printf("You found a SHIELD!\n");
32    playerFlags |= HAS_SHIELD;
33    printInventory(playerFlags);
34    
35    // Use potion (can't - don't have one!)
36    if (playerFlags & HAS_POTION) {
37        printf("Used potion!\n");
38        playerFlags &= ~HAS_POTION;
39    } else {
40        printf("No potion to use!\n");
41    }
42    
43    // Pick up potion
44    printf("You found a POTION!\n");
45    playerFlags |= HAS_POTION;
46    printInventory(playerFlags);
47    
48    // Complete quest
49    printf("QUEST COMPLETE!\n");
50    playerFlags |= QUEST_COMPLETE;
51    printInventory(playerFlags);
52    
53    // Check if ready for boss (need sword AND shield)
54    if ((playerFlags & HAS_SWORD) && (playerFlags & HAS_SHIELD)) {
55        printf("\nYou are ready to fight the boss!\n");
56    }
57    
58    return 0;
59}

Output

=== Adventure Game ===

Inventory: [Empty]

You found a SWORD!

Inventory: [Sword]

You found a SHIELD!

Inventory: [Sword] [Shield]

No potion to use!

You found a POTION!

Inventory: [Sword] [Shield] [Potion]

QUEST COMPLETE!

Inventory: [Sword] [Shield] [Potion] [Quest✓]

You are ready to fight the boss!

!Code Pitfalls: Common Mistakes & What to Watch For

Common Mistakes with Bitmasks

Copying code often make subtle errors with bitwise operations:

✗Confusing & and &&: Code often uses logical AND when bitwise AND is needed, or vice versa
✗Precedence mistakes: Beginners often forget that == has higher precedence than &, writing x & FLAG == 0
✗Wrong bit position: Beginners often count bits from wrong end or uses 1-based instead of 0-based indexing
✗Sign extension issues: Beginners often shift signed integers without considering sign bit behavior

Always Understand Before Using

Test bitmask operations with specific values and trace the binary. Use parentheses liberally: (x & FLAG) == 0 not x & FLAG == 0. Use unsigned types for shifting to avoid sign extension surprises.

07Frequently Asked Questions

Q:What are common bit manipulation patterns I should memorize?

A: Key patterns:x | mask sets bits,x & ~mask clears bits,x ^ mask toggles bits,x & mask tests bits,x & (x-1) clears lowest set bit,x & -x isolates lowest set bit. These patterns appear constantly in systems programming and interviews.

Q:Why use bitmasks instead of multiple booleans?

A: Memory efficiency! 8 booleans = 8 bytes; 8 flags in one byte. Plus you can pass all flags as a single integer, combine flags with OR, and test multiple conditions in one operation. Common in system APIs and embedded programming.

Q:How do I count the number of set bits?

A: This is called "popcount" (population count). Loop through and test each bit, or use GCC's builtin:__builtin_popcount(x). This is useful for counting active flags or in algorithms like Hamming distance.

Q:How do I find the lowest/highest set bit?

A: For lowest set bit:x & (-x) isolates it. For position, use__builtin_ctz(x) (count trailing zeros). For highest bit, use __builtin_clz(x) (count leading zeros). These are crucial for efficient bitboard algorithms and priority queues.

Q:What does 1 << n mean?

A: Left shift 1 by n positions, creating a number with only bit n set. 1 << 0 = 1,1 << 3 = 8 (binary 1000). This is how we create masks for individual bit positions.

Q:How do I combine multiple flags?

A: Use OR:READ | WRITE | EXECUTE combines all three. This is why you see function calls likeopen("file", O_RDWR | O_CREAT).

Q:How do I check if a number is a power of 2?

A: Use the expression(n > 0) && ((n & (n - 1)) == 0). Powers of 2 have exactly one bit set, so n & (n-1) clears that bit, giving 0. This is a classic bit manipulation trick used in allocators and hash tables.

Q:How do I swap two values without a temp variable?

A: XOR swap:a ^= b; b ^= a; a ^= b;This works because XOR is its own inverse. However, this is mainly a curiosity— modern compilers optimize regular swaps better, and XOR swap fails if a and b are the same variable.

Q:What's the ~ operator?

A: Bitwise NOT — flips all bits.~(1 << 3) = 11110111. Used to create masks for clearing bits: x & ~FLAG clears that flag while keeping all others.

Q:Where are bitmasks used in real programming?

A: File permissions (Unix), network packet headers, CPU flags, feature toggles, compression algorithms, graphics (color channels), game states, embedded systems, and low-level hardware control.

07Summary

Key Takeaways

•Bitmask: Pattern of bits as flags
•Set bit: x | (1 << n)
•Clear bit: x & ~(1 << n)
•Toggle bit: x ^ (1 << n)
•Check bit: (x >> n) & 1
•Use cases: Permissions, flags, hardware, games
•Memory efficient: Store 8+ flags in one byte
•Combine flags: Use OR to set multiple: READ | WRITE
•Test flags: Use AND to check if a flag is set
•Best practice: Define flags with meaningful names using #define or enum

08When to Use Bitmasks

Perfect for Compact Flag Storage

Use bitmasks when you have multiple boolean options that are often passed together, like file permissions or window styles. They're also ideal for hardware registers and protocols where every bit has meaning. Avoid them when code clarity matters more than memory—separate booleans are often easier to understand.

?Why Do We Need Bitmasks?

Imagine storing 8 yes/no settings. You could use 8 bool variables (8 bytes), or use 1 byte with bitmasks. Bitmasks are essential for:

File Permissions

chmod 755 uses octal bitmasks:

rwx = 111 = 7 (Owner)
r-x = 101 = 5 (Group)
r-x = 101 = 5 (Others)

Game Development

Store player states, power-ups, collision layers — all in compact bit flags.

Hardware & Embedded

Control registers in microcontrollers are all bit fields.

Network Protocols

TCP/IP headers pack multiple flags into single bytes.

Memory savings: Storing 32 boolean flags takes 32 bytes with bool, but only 4 bytes with bitmasks — 8× more efficient!

01What are Bitmasks?

• Simple Definition

A bitmask is a pattern of bits used to manipulate individual bits within a number. Each bit acts as an ON/OFF flag!

Key Benefits

Memory Efficient

Store 8 flags in 1 byte!

Fast Operations

Bitwise ops are very fast

Permissions

Read, Write, Execute flags

Hardware Control

Control device registers

02Bitwise Operators Review

Operator	Name	Description	Example
&	AND	1 if both bits are 1	5 & 3 = 1
\|	OR	1 if either bit is 1	5 \| 3 = 7
^	XOR	1 if bits are different	5 ^ 3 = 6
~	NOT	Flip all bits	~5 = -6
<<	Left Shift	Shift bits left	5 << 1 = 10
>>	Right Shift	Shift bits right	5 >> 1 = 2

03Understanding Binary: Visual Guide

# 8-bit Number Visualization

Each bit position has a power-of-2 value. To get the decimal value, add up where bits are 1.

bit 7

bit 6

bit 5

bit 4

bit 3

bit 2

bit 1

bit 0

128

Example: 13 in binary

8 + 4 + 1 = 13

04Common Bitmask Operations

Visual: Set Bit 2 of value 9

Value: 9 = 0000 1001

Mask: 1 << 2 = 0000 0100

| (OR)

Result: 13 = 0000 1101

Operation	Code	Description
Set bit	x \| (1 << n)	Turn bit n ON (use OR with mask)
Clear bit	x & ~(1 << n)	Turn bit n OFF (AND with inverted mask)
Toggle bit	x ^ (1 << n)	Flip bit n (XOR toggles)
Check bit	(x >> n) & 1	Is bit n set? (returns 0 or 1)

bitmask_operations.c

1#include <stdio.h>
2
3// Helper function to print binary
4void printBinary(unsigned int n, int bits) {
5    for (int i = bits - 1; i >= 0; i--) {
6        printf("%d", (n >> i) & 1);
7    }
8}
9
10int main() {
11    unsigned int x = 0b00001010;  // Start with 10
12    
13    printf("Original:    ");
14    printBinary(x, 8);
15    printf(" = %d\n", x);
16    
17    // SET bit 0 (rightmost)
18    x = x | (1 << 0);
19    printf("Set bit 0:   ");
20    printBinary(x, 8);
21    printf(" = %d\n", x);
22    
23    // SET bit 4
24    x = x | (1 << 4);
25    printf("Set bit 4:   ");
26    printBinary(x, 8);
27    printf(" = %d\n", x);
28    
29    // CLEAR bit 1
30    x = x & ~(1 << 1);
31    printf("Clear bit 1: ");
32    printBinary(x, 8);
33    printf(" = %d\n", x);
34    
35    // TOGGLE bit 3
36    x = x ^ (1 << 3);
37    printf("Toggle bit 3:");
38    printBinary(x, 8);
39    printf(" = %d\n", x);
40    
41    // CHECK if bit 4 is set
42    if ((x >> 4) & 1) {
43        printf("Bit 4 is SET\n");
44    } else {
45        printf("Bit 4 is NOT set\n");
46    }
47    
48    return 0;
49}

Output

Original: 00001010 = 10

Set bit 0: 00001011 = 11

Set bit 4: 00011011 = 27

Clear bit 1: 00011001 = 25

Toggle bit 3:00010001 = 17

Bit 4 is SET

04Practical Example: File Permissions

permissions.c

1#include <stdio.h>
2
3// Define permission flags using bit positions
4#define READ    (1 << 0)  // 001 = 1
5#define WRITE   (1 << 1)  // 010 = 2
6#define EXECUTE (1 << 2)  // 100 = 4
7
8void printPermissions(int perms) {
9    printf("Permissions: ");
10    if (perms & READ)    printf("Read ");
11    if (perms & WRITE)   printf("Write ");
12    if (perms & EXECUTE) printf("Execute ");
13    printf("\n");
14}
15
16int main() {
17    int permissions = 0;  // No permissions
18    
19    printf("=== File Permission System ===\n\n");
20    
21    // Grant READ permission
22    permissions |= READ;
23    printf("After granting READ:\n");
24    printPermissions(permissions);
25    
26    // Grant WRITE permission
27    permissions |= WRITE;
28    printf("After granting WRITE:\n");
29    printPermissions(permissions);
30    
31    // Grant EXECUTE permission
32    permissions |= EXECUTE;
33    printf("After granting EXECUTE:\n");
34    printPermissions(permissions);
35    
36    // Revoke WRITE permission
37    permissions &= ~WRITE;
38    printf("After revoking WRITE:\n");
39    printPermissions(permissions);
40    
41    // Check specific permission
42    if (permissions & EXECUTE) {
43        printf("\nUser CAN execute this file.\n");
44    }
45    
46    if (!(permissions & WRITE)) {
47        printf("User CANNOT write to this file.\n");
48    }
49    
50    // Grant multiple at once
51    int fullAccess = READ | WRITE | EXECUTE;
52    printf("\nFull access value: %d (binary: ", fullAccess);
53    for (int i = 2; i >= 0; i--) printf("%d", (fullAccess >> i) & 1);
54    printf(")\n");
55    
56    return 0;
57}

Output

=== File Permission System ===

After granting READ:

Permissions: Read

After granting WRITE:

Permissions: Read Write

After granting EXECUTE:

Permissions: Read Write Execute

After revoking WRITE:

Permissions: Read Execute

User CAN execute this file.

User CANNOT write to this file.

Full access value: 7 (binary: 111)

05Practical Example: Game Flags

game_flags.c

1#include <stdio.h>
2
3// Game state flags
4#define HAS_SWORD      (1 << 0)  // 0001
5#define HAS_SHIELD     (1 << 1)  // 0010
6#define HAS_POTION     (1 << 2)  // 0100
7#define QUEST_COMPLETE (1 << 3)  // 1000
8
9void printInventory(int flags) {
10    printf("Inventory: ");
11    if (flags & HAS_SWORD)      printf("[Sword] ");
12    if (flags & HAS_SHIELD)     printf("[Shield] ");
13    if (flags & HAS_POTION)     printf("[Potion] ");
14    if (flags & QUEST_COMPLETE) printf("[Quest✓] ");
15    if (flags == 0)             printf("[Empty]");
16    printf("\n");
17}
18
19int main() {
20    int playerFlags = 0;
21    
22    printf("=== Adventure Game ===\n\n");
23    printInventory(playerFlags);
24    
25    // Pick up sword
26    printf("You found a SWORD!\n");
27    playerFlags |= HAS_SWORD;
28    printInventory(playerFlags);
29    
30    // Pick up shield
31    printf("You found a SHIELD!\n");
32    playerFlags |= HAS_SHIELD;
33    printInventory(playerFlags);
34    
35    // Use potion (can't - don't have one!)
36    if (playerFlags & HAS_POTION) {
37        printf("Used potion!\n");
38        playerFlags &= ~HAS_POTION;
39    } else {
40        printf("No potion to use!\n");
41    }
42    
43    // Pick up potion
44    printf("You found a POTION!\n");
45    playerFlags |= HAS_POTION;
46    printInventory(playerFlags);
47    
48    // Complete quest
49    printf("QUEST COMPLETE!\n");
50    playerFlags |= QUEST_COMPLETE;
51    printInventory(playerFlags);
52    
53    // Check if ready for boss (need sword AND shield)
54    if ((playerFlags & HAS_SWORD) && (playerFlags & HAS_SHIELD)) {
55        printf("\nYou are ready to fight the boss!\n");
56    }
57    
58    return 0;
59}

Output

=== Adventure Game ===

Inventory: [Empty]

You found a SWORD!

Inventory: [Sword]

You found a SHIELD!

Inventory: [Sword] [Shield]

No potion to use!

You found a POTION!

Inventory: [Sword] [Shield] [Potion]

QUEST COMPLETE!

Inventory: [Sword] [Shield] [Potion] [Quest✓]

You are ready to fight the boss!

!Code Pitfalls: Common Mistakes & What to Watch For

Common Mistakes with Bitmasks

Copying code often make subtle errors with bitwise operations:

✗Confusing & and &&: Code often uses logical AND when bitwise AND is needed, or vice versa
✗Precedence mistakes: Beginners often forget that == has higher precedence than &, writing x & FLAG == 0
✗Wrong bit position: Beginners often count bits from wrong end or uses 1-based instead of 0-based indexing
✗Sign extension issues: Beginners often shift signed integers without considering sign bit behavior

Always Understand Before Using

Test bitmask operations with specific values and trace the binary. Use parentheses liberally: (x & FLAG) == 0 not x & FLAG == 0. Use unsigned types for shifting to avoid sign extension surprises.

07Frequently Asked Questions

Q:What are common bit manipulation patterns I should memorize?

Q:Why use bitmasks instead of multiple booleans?

Q:How do I count the number of set bits?

Q:How do I find the lowest/highest set bit?

Q:What does 1 << n mean?

A: Left shift 1 by n positions, creating a number with only bit n set. 1 << 0 = 1,1 << 3 = 8 (binary 1000). This is how we create masks for individual bit positions.

Q:How do I combine multiple flags?

A: Use OR:READ | WRITE | EXECUTE combines all three. This is why you see function calls likeopen("file", O_RDWR | O_CREAT).

Q:How do I check if a number is a power of 2?

Q:How do I swap two values without a temp variable?

Q:What's the ~ operator?

A: Bitwise NOT — flips all bits.~(1 << 3) = 11110111. Used to create masks for clearing bits: x & ~FLAG clears that flag while keeping all others.

Q:Where are bitmasks used in real programming?

A: File permissions (Unix), network packet headers, CPU flags, feature toggles, compression algorithms, graphics (color channels), game states, embedded systems, and low-level hardware control.

07Summary

Key Takeaways

•Bitmask: Pattern of bits as flags
•Set bit: x | (1 << n)
•Clear bit: x & ~(1 << n)
•Toggle bit: x ^ (1 << n)
•Check bit: (x >> n) & 1
•Use cases: Permissions, flags, hardware, games
•Memory efficient: Store 8+ flags in one byte
•Combine flags: Use OR to set multiple: READ | WRITE
•Test flags: Use AND to check if a flag is set
•Best practice: Define flags with meaningful names using #define or enum

What You Will Learn

?Why Do We Need Bitmasks?

File Permissions

Game Development

Hardware & Embedded

Network Protocols

01What are Bitmasks?

• Simple Definition

Key Benefits

02Bitwise Operators Review

03Understanding Binary: Visual Guide

# 8-bit Number Visualization

04Common Bitmask Operations

Visual: Set Bit 2 of value 9

04Practical Example: File Permissions

05Practical Example: Game Flags

!Code Pitfalls: Common Mistakes & What to Watch For

Common Mistakes with Bitmasks

Always Understand Before Using

07Frequently Asked Questions

Q:What are common bit manipulation patterns I should memorize?

Q:Why use bitmasks instead of multiple booleans?

Q:How do I count the number of set bits?

Q:How do I find the lowest/highest set bit?

Q:What does 1 << n mean?

Q:How do I combine multiple flags?

Q:How do I check if a number is a power of 2?

Q:How do I swap two values without a temp variable?

Q:What's the ~ operator?

Q:Where are bitmasks used in real programming?

07Summary

Key Takeaways

08When to Use Bitmasks

Perfect for Compact Flag Storage

Test Your Knowledge

Related Tutorials

Bit Fields in Structures

Function Pointers in C

const and volatile Keywords

Have Feedback?

What You Will Learn

?Why Do We Need Bitmasks?

File Permissions

Game Development

Hardware & Embedded

Network Protocols

01What are Bitmasks?

• Simple Definition

Key Benefits

02Bitwise Operators Review

03Understanding Binary: Visual Guide

# 8-bit Number Visualization

04Common Bitmask Operations

Visual: Set Bit 2 of value 9

04Practical Example: File Permissions

05Practical Example: Game Flags

!Code Pitfalls: Common Mistakes & What to Watch For

Common Mistakes with Bitmasks

Always Understand Before Using

07Frequently Asked Questions

Q:What are common bit manipulation patterns I should memorize?

Q:Why use bitmasks instead of multiple booleans?

Q:How do I count the number of set bits?

Q:How do I find the lowest/highest set bit?

Q:What does 1 << n mean?

Q:How do I combine multiple flags?

Q:How do I check if a number is a power of 2?

Q:How do I swap two values without a temp variable?

Q:What's the ~ operator?

Q:Where are bitmasks used in real programming?

07Summary

Key Takeaways

08When to Use Bitmasks

Perfect for Compact Flag Storage

Test Your Knowledge

Related Tutorials

Bit Fields in Structures

Function Pointers in C

const and volatile Keywords

Have Feedback?