Understanding Bytes, Bits, and Data Types in C++

If you’ve ever wondered how numbers are stored in C++ and what terms like signed, unsigned this guide is for you! Let’s break everything down step-by-step in the simplest way possible.

What are Bits and Bytes?

• Bit = Smallest piece of data in computers (either 0 or 1 → like a light switch: OFF or ON)
• Byte = Group of 8 bits (1 Byte = 8 Bits)

🔢 Example: How Many Bytes Does 10000 Use?

To store 10000, we must first convert it to binary:

Final Binary: 10011100010000 → 14 bits

So 10000 needs 14 bits, which fits inside 2 bytes (16 bits).

We can use the short data type to store this.

📊 C++ Integer Types – Size, Range & Use Cases

char – For Single Characters

• You want to store a single character like 'A', '5', or '#' -Internally, it’s stored as a number using ASCII codes (e.g., 'A' = 65)

Use When:

• Saving memory with small numbers
• Embedded systems or memory-limited devices

Example:

char grade = 'A';
char symbol = '#';

short

• Size: 2 bytes (16 bits)
• Range: –32,768 to 32,767

Use When:

• Saving memory with small numbers
• Embedded systems or memory-limited devices

Avoid For:

• Storing full words or big numbers
• Large values like bank balances

Example:

short age = 22;
short temp = -10;

int

• Size: 4 bytes (32 bits)
• Range: –2,147,483,648 to +2,147,483,647

✅ Use When:

• General-purpose integer storage
• Loop counters, indexes, calculations

🧾 Example:

int population = 1000000;
int marks = 95;

long

• Size:
  • 4 bytes on 32-bit systems
  • 8 bytes on most 64-bit Linux/macOS systems
• Range: Varies with size

✅ Use When:

• You need bigger numbers than int but smaller than long long
• Storing large IDs, timestamps

🧾 Example:

long distance = 123456789;

💡 Note:
Windows 64-bit uses LLP64 model: long = 4 bytes
Linux/macOS 64-bit use LP64 model: long = 8 bytes

long long

• Size: 8 bytes (64 bits)

✅ Use When:

• Handling very large numbers that don’t fit in int or long
• Competitive programming, large calculations, finance

🧾 Example:

long long bigAmount = 1000000000000;

What Do Signed and Unsigned Mean?

Imagine a number line:

<---- -3 -2 -1 0 1 2 3 ---->

🔁 Signed

• Can hold both negative and positive numbers
• Uses one bit to indicate the sign (0 = positive, 1 = negative)
• For 2 bytes (16 bits): Range = –32,768 to +32,767

➕ Unsigned

• Can hold only positive numbers (including zero)
• All bits are used to store the value
• For 2 bytes (16 bits): Range = 0 to 65,535

🔓 Real-life Analogy

You have 16 lockers (bits):

• If storing only positive numbers (unsigned), all 16 lockers are used for the value.
• If storing positive and negative numbers (signed), 1 locker is used for the sign, and 15 lockers are used for the number itself.