Bit-field Flags Demo
Hard
C
Structures
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Problem Statement
Structure with 5 different status flags stored (isActive, isPaid, isVerified, etc.) using bit-fields. Memory saving calculated using vs normal approach.
Input Format
No user input.
A structure is defined using status flags.
A structure is defined using status flags.
Output Format
Memory usage comparison:
• Normal structure
• Bit-field structure
• Normal structure
• Bit-field structure
Example
Status flags: isActive, isPaid, isVerified, isAdmin, isBlocked
Normal structure size = 20 bytes Bit-field structure size = 4 bytes Memory saved = 16 bytes
Constraints
• Total flags = 5
• Each flag stores only true/false
• Each flag stores only true/false
Concept Explanation
Each status flag needs only 1 bit (0 or 1).
Using normal int variables wastes memory.
Bit-fields store flags in bits, saving memory.
Using normal int variables wastes memory.
Bit-fields store flags in bits, saving memory.
Step-by-Step Explanation
Normal Approach
1.Create a structure with 5 int variables.
2.Each int takes 4 bytes.
3.Total memory used:
• 5 × 4 = 20 bytes.
Bit-field Approach
1.Create a structure with 5 bit-fields of size 1.
2.Each flag uses 1 bit.
3.Total bits used:
• 5 bits.
4.These bits fit inside 1 integer (4 bytes).
Memory Saving
1.Normal structure size = 20 bytes.
2.Bit-field structure size = 4 bytes.
3.Memory saved = 16 bytes.
1.Create a structure with 5 int variables.
2.Each int takes 4 bytes.
3.Total memory used:
• 5 × 4 = 20 bytes.
Bit-field Approach
1.Create a structure with 5 bit-fields of size 1.
2.Each flag uses 1 bit.
3.Total bits used:
• 5 bits.
4.These bits fit inside 1 integer (4 bytes).
Memory Saving
1.Normal structure size = 20 bytes.
2.Bit-field structure size = 4 bytes.
3.Memory saved = 16 bytes.
Concept Explanation
Each status flag needs only 1 bit (0 or 1).
Using normal int variables wastes memory.
Bit-fields store flags in bits, saving memory.
Using normal int variables wastes memory.
Bit-fields store flags in bits, saving memory.
Step-by-Step Explanation
Normal Approach
1.Create a structure with 5 int variables.
2.Each int takes 4 bytes.
3.Total memory used:
• 5 × 4 = 20 bytes.
Bit-field Approach
1.Create a structure with 5 bit-fields of size 1.
2.Each flag uses 1 bit.
3.Total bits used:
• 5 bits.
4.These bits fit inside 1 integer (4 bytes).
Memory Saving
1.Normal structure size = 20 bytes.
2.Bit-field structure size = 4 bytes.
3.Memory saved = 16 bytes.
1.Create a structure with 5 int variables.
2.Each int takes 4 bytes.
3.Total memory used:
• 5 × 4 = 20 bytes.
Bit-field Approach
1.Create a structure with 5 bit-fields of size 1.
2.Each flag uses 1 bit.
3.Total bits used:
• 5 bits.
4.These bits fit inside 1 integer (4 bytes).
Memory Saving
1.Normal structure size = 20 bytes.
2.Bit-field structure size = 4 bytes.
3.Memory saved = 16 bytes.
Input / Output Format
Input Format
No user input.
A structure is defined using status flags.
A structure is defined using status flags.
Output Format
Memory usage comparison:
• Normal structure
• Bit-field structure
• Normal structure
• Bit-field structure
Constraints
• Total flags = 5
• Each flag stores only true/false
• Each flag stores only true/false
Examples
Input:
Status flags:
isActive, isPaid, isVerified, isAdmin, isBlocked
Output:
Normal structure size = 20 bytes
Bit-field structure size = 4 bytes
Memory saved = 16 bytes
Example Solution (Public)
#include <stdio.h>
// Structure with bit-fields (1 bit each)
struct StatusBitField {
unsigned int isActive : 1;
unsigned int isPaid : 1;
unsigned int isVerified : 1;
unsigned int isAdmin : 1;
unsigned int isBanned : 1;
};
// Normal structure (no bit-fields)
struct StatusNormal {
unsigned int isActive;
unsigned int isPaid;
unsigned int isVerified;
unsigned int isAdmin;
unsigned int isBanned;
};
int main() {
struct StatusBitField sBit;
struct StatusNormal sNormal;
printf("Size of structure with bit-fields: %lu bytesn", sizeof(sBit));
printf("Size of normal structure: %lu bytesn", sizeof(sNormal));
// Example of setting values
sBit.isActive = 1;
sBit.isPaid = 0;
sBit.isVerified = 1;
sBit.isAdmin = 0;
sBit.isBanned = 0;
printf("nBit-field values:n");
printf("isActive: %un", sBit.isActive);
printf("isPaid: %un", sBit.isPaid);
printf("isVerified: %un", sBit.isVerified);
printf("isAdmin: %un", sBit.isAdmin);
printf("isBanned: %un", sBit.isBanned);
return 0;
}
Official Solution Code
#include <stdio.h>
// Structure with bit-fields (1 bit each)
struct StatusBitField {
unsigned int isActive : 1;
unsigned int isPaid : 1;
unsigned int isVerified : 1;
unsigned int isAdmin : 1;
unsigned int isBanned : 1;
};
// Normal structure (no bit-fields)
struct StatusNormal {
unsigned int isActive;
unsigned int isPaid;
unsigned int isVerified;
unsigned int isAdmin;
unsigned int isBanned;
};
int main() {
struct StatusBitField sBit;
struct StatusNormal sNormal;
printf("Size of structure with bit-fields: %lu bytesn", sizeof(sBit));
printf("Size of normal structure: %lu bytesn", sizeof(sNormal));
// Example of setting values
sBit.isActive = 1;
sBit.isPaid = 0;
sBit.isVerified = 1;
sBit.isAdmin = 0;
sBit.isBanned = 0;
printf("nBit-field values:n");
printf("isActive: %un", sBit.isActive);
printf("isPaid: %un", sBit.isPaid);
printf("isVerified: %un", sBit.isVerified);
printf("isAdmin: %un", sBit.isAdmin);
printf("isBanned: %un", sBit.isBanned);
return 0;
}
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