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

sushi — Sun, 25 May 2025 22:06:36 +0000

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)

Bytes	Bits
1	8
2	16
4	32

🔢 Example: How Many Bytes Does `10000` Use?

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

Step	Division	Quotient	Remainder
1	10000 ÷ 2	5000	0
2	5000 ÷ 2	2500	0
3	2500 ÷ 2	1250	0
4	1250 ÷ 2	625	0
5	625 ÷ 2	312	1
6	312 ÷ 2	156	0
7	156 ÷ 2	78	0
8	78 ÷ 2	39	0
9	39 ÷ 2	19	1
10	19 ÷ 2	9	1
11	9 ÷ 2	4	1
12	4 ÷ 2	2	0
13	2 ÷ 2	1	0
14	1 ÷ 2	0	1

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.

DEV Community: sushi

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

What are Bits and Bytes?

🔢 Example: How Many Bytes Does 10000 Use?

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

char – For Single Characters

Use When:

Example:

short

Use When:

Avoid For:

Example:

int

✅ Use When:

🧾 Example:

long

✅ Use When:

🧾 Example:

long long

✅ Use When:

🧾 Example:

What Do Signed and Unsigned Mean?

🔁 Signed

➕ Unsigned

🔓 Real-life Analogy

🔢 Example: How Many Bytes Does `10000` Use?

`char` – For Single Characters

`short`

`int`

`long`

`long long`