Primitive Types (int, double, char, bool) & Fixed-Width Integers (cstdint)0%

Primitive Types (int, double, char, bool) & Fixed-Width Integers (cstdint)

Beginner13 min read•Updated: 2026-10-22

🔢 Primitive Types & Fixed-Width Integers (cstdint)

Introduction

Data in C++ is stored in memory cells governed by data types. Because traditional C++ fundamental types (int, long) can change their byte size depending on compiler architecture (32-bit vs 64-bit Windows vs Linux), modern systems programming demands fixed-width types from <cstdint>.

📊 Traditional Fundamental Types

Type	Typical Size	Typical Range
`bool`	1 byte	`true` (1) or `false` (0)
`char`	1 byte	-128 to 127 or 0 to 255
`int`	4 bytes	-2,147,483,648 to 2,147,483,647
`float`	4 bytes	~7 decimal digits of precision
`double`	8 bytes	~15-17 decimal digits of precision

1#include <iostream>
2 
3int main() {
4    std::cout << "bool: " << sizeof(bool) << " byte(s)\n";
5    std::cout << "char: " << sizeof(char) << " byte(s)\n";
6    std::cout << "int: " << sizeof(int) << " byte(s)\n";
7    std::cout << "double: " << sizeof(double) << " byte(s)\n";
8    return 0;
9}

🛡️ Modern Fixed-Width Types (`<cstdint>`)

When building cross-platform networking, binary serialization, or graphics engines, always use explicit width integers:

1#include <iostream>
2#include <cstdint>
3 
4int main() {
  int8_t  smallInt = -120;     // Exactly 8 bits signed (-128 to 127)
  uint8_t byteData = 255;      // Exactly 8 bits unsigned (0 to 255)
  
  int16_t audioSample = -32000;// Exactly 16 bits (-32768 to 32767)
  uint16_t portNumber = 8080;  // Exactly 16 bits unsigned (0 to 65535)
  
  int32_t userBalance = -5000; // Exactly 32 bits signed
  uint32_t ipAddress = 0xC0A80001; // Exactly 32 bits unsigned
  
  int64_t nanoSeconds = 1000000000000LL; // Exactly 64 bits signed
  uint64_t fileSize = 15482930219ULL;    // Exactly 64 bits unsigned
  
  std::cout << "Port: " << portNumber << ", Size: " << sizeof(fileSize) << " bytes\n";
  return 0;
19}

💡 Best Practices:

1
Use double for general floating-point math (float has severe precision truncation in financial calculations).
2
Use std::size_t from <cstddef> when indexing containers or counting bytes.
3
Avoid raw unsigned int for loops unless counting bitfields, to prevent underflow rollover bugs.

Next Lesson

Type Deduction with auto and decltype

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

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Comments, Indentation, and Modern C++ Coding Guidelines	Type Deduction with auto and decltype

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Type Deduction with auto and decltype

Primitive Types (int, double, char, bool) & Fixed-Width Integers (cstdint)

Beginner13 min read•Updated: 2026-10-22

Study Materials

🔢 Primitive Types & Fixed-Width Integers (cstdint)

Introduction

📊 Traditional Fundamental Types

Type	Typical Size	Typical Range
`bool`	1 byte	`true` (1) or `false` (0)
`char`	1 byte	-128 to 127 or 0 to 255
`int`	4 bytes	-2,147,483,648 to 2,147,483,647
`float`	4 bytes	~7 decimal digits of precision
`double`	8 bytes	~15-17 decimal digits of precision

1#include <iostream>
2 
3int main() {
4    std::cout << "bool: " << sizeof(bool) << " byte(s)\n";
5    std::cout << "char: " << sizeof(char) << " byte(s)\n";
6    std::cout << "int: " << sizeof(int) << " byte(s)\n";
7    std::cout << "double: " << sizeof(double) << " byte(s)\n";
8    return 0;
9}

🛡️ Modern Fixed-Width Types (`<cstdint>`)

When building cross-platform networking, binary serialization, or graphics engines, always use explicit width integers:

1#include <iostream>
2#include <cstdint>
3 
4int main() {
  int8_t  smallInt = -120;     // Exactly 8 bits signed (-128 to 127)
  uint8_t byteData = 255;      // Exactly 8 bits unsigned (0 to 255)
  
  int16_t audioSample = -32000;// Exactly 16 bits (-32768 to 32767)
  uint16_t portNumber = 8080;  // Exactly 16 bits unsigned (0 to 65535)
  
  int32_t userBalance = -5000; // Exactly 32 bits signed
  uint32_t ipAddress = 0xC0A80001; // Exactly 32 bits unsigned
  
  int64_t nanoSeconds = 1000000000000LL; // Exactly 64 bits signed
  uint64_t fileSize = 15482930219ULL;    // Exactly 64 bits unsigned
  
  std::cout << "Port: " << portNumber << ", Size: " << sizeof(fileSize) << " bytes\n";
  return 0;
19}

💡 Best Practices:

1
Use double for general floating-point math (float has severe precision truncation in financial calculations).
2
Use std::size_t from <cstddef> when indexing containers or counting bytes.
3
Avoid raw unsigned int for loops unless counting bitfields, to prevent underflow rollover bugs.

Next Lesson

Type Deduction with auto and decltype

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Comments, Indentation, and Modern C++ Coding Guidelines	Type Deduction with auto and decltype

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next

🔢 Primitive Types & Fixed-Width Integers (cstdint)

Introduction

📊 Traditional Fundamental Types

🛡️ Modern Fixed-Width Types (<cstdint>)

💡 Best Practices:

Type Deduction with auto and decltype

Related Lessons

Practice Quiz

Loading Page Content...

🔢 Primitive Types & Fixed-Width Integers (cstdint)

Introduction

📊 Traditional Fundamental Types

🛡️ Modern Fixed-Width Types (<cstdint>)

💡 Best Practices:

Type Deduction with auto and decltype

Related Lessons

Practice Quiz

🛡️ Modern Fixed-Width Types (`<cstdint>`)

🛡️ Modern Fixed-Width Types (`<cstdint>`)