Fundamental Data Types in C++

Fundamental Data Types in C++

📘 Overview C++ fundamental types represent integral values, floating-point values, the absence of a value, and null pointers. A type determines a value's representation, range, and permitted operations; std::string and arrays are not fundamental types.

🧠 Key Idea Choose a fundamental type according to the values and operations a program requires. Type sizes, numeric precision, and conversion rules determine whether those values are represented correctly.

⚔️ Core Details: - Integral types include bool, character types, and signed or unsigned integer types such as short, int, long, and long long. - bool has exactly two values: true and false. - Floating-point types are float, double, and long double, with nondecreasing precision in that order. - sizeof(char) is always one byte; the number of bits per byte and the sizes of most other fundamental types depend on the implementation. - void denotes the absence of a value; std::nullptr_t is the fundamental type of the null pointer literal nullptr. - Brace initialization rejects narrowing conversions, such as converting a fractional double value to int.

🎯 Why It Matters: - Portable programs avoid assuming that int is always thirty-two bits or that a byte always contains eight bits. - Unsigned arithmetic wraps around, while signed integer overflow causes undefined behavior; choosing a type changes program correctness. - Floating-point rounding can make exact equality unreliable for computed results. - Explicit initialization prevents accidental use of indeterminate values in automatic local variables.

🧠 Quick Recall: - Integer division - Division of two integer operands produces an integer result truncated toward zero. - Character types - Plain char, signed char, and unsigned char are distinct types; plain char's signedness is implementation-defined. - Unsigned range - An unsigned integer type with $N$