Exploring C Language Data Types: Integer, Floating-Point, and Character Types – A Must-Read for Programmers!

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The data types in C define how variables are stored, their range of values, and the operations that can be performed on them. Mastering the basic data types is key to writing efficient programs. This section introduces three core types: Integer, Floating-Point, and Character.

1. Integer Types (整型)

Integers are used to represent whole numbers and are divided into different subtypes, distinguished by memory usage and value range:

Type	Typical Bytes	Value Range (signed)	Description
short	2 bytes	-32768 ~ 32767	Short integer, suitable for small range integers
int	4 bytes	-2³¹ ~ 2³¹-1	Default integer, balancing memory and performance
long	4 or 8 bytes	-2³¹ ~ 2³¹-1 or larger	Long integer, compatibility depends on compiler and system
long long	8 bytes	-2⁶³ ~ 2⁶³-1	New in C99, extremely large integer range

Modifiers:

– `signed` (default): includes both positive and negative values, such as `signed int`.

– `unsigned`: only non-negative values, doubling the range, such as `unsigned short` (0 ~ 65535).

Example:

2. Floating-Point Types (浮点型)

Floating-point types represent decimal or scientific notation values, supporting single and double precision:

Type	Bytes	Precision	Typical Value Range (absolute value)
float	4 bytes	about6~7 decimal places	1.2e-38 ~ 3.4e38
double	8 bytes	about15~16 decimal places	2.3e-308 ~ 1.7e308
long double	8~16	Higher precision	Depends on compiler implementation

Note:

– Floating-point operations may have precision errors (e.g., `0.1 + 0.2 != 0.3`), avoid precise comparisons.

– Default floating-point literals (e.g., `3.14`) are of type `double` and adding `f` suffix indicates `float` (e.g., `3.14f`).

Example:

3. Character Type (字符型)

The character type (`char`) stores a single character, actually stored as an **ASCII** code integer value, occupying 1 byte:

Type	Bytes	Value Range (signed)	Description
char	1 byte	-128 ~ 127 or 0~255	Specific range depends on whether the compiler is signed

Characteristics:

– Characters are enclosed in single quotes (e.g., `’A’`), supporting escape sequences (e.g., `’
‘` for newline).

– `char` can interoperate with integers (e.g., `char c = 65;` is equivalent to `’A’`).

Example:

Summary

– Integers: choose `short`, `int` or `long` based on value range and memory needs.

– Floating-point: prefer `double` for precision, use `float` when memory is a concern.

– Character: handle text or small range integers, note that sign depends on the compilation environment.

Choosing the right data type can optimize program performance and memory usage while avoiding overflow or precision loss issues.

ENDC Language

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