C Learning Notes (i) data, operators, expressions

Note: Based on learning rectification C program design, online search for personal summary of some practical application of knowledge

The data has integer type, floating point type, character type data

(1) Define Integer data:

Integer (int) 16-bit 2-byte -32768~32767

Short int 16 bits 2 bytes -32768~32767

Long int 32 bits 4 bytes

unsigned integer (unsigned int) 16-bit 2-byte 0~65535

unsigned short integer (unsigned) 16-bit 2-byte 0~65535

unsigned long integer (unsigned long int) 32 bits 4 bytes

Decimal, octal (0 flag), Hex (0x flag)

(2) Define floating-point data:

Single-precision floating-point (float) 32-bit 4-byte

Double-precision floating-point (double) 64-bit 8-byte

Long double precision floating point type (long double) 128 bits

Note: Floating-point data operations sometimes have rounding errors

(3) Define the character type data:

Character data (char) 8 bits 1 bytes

unsigned character data (unsigned char) 8 bits 1 bytes

(4) Constants

Integral type constant: 1,2,3,4 ...

Real constants: 1.2,-0.12 ....

Character constants: ' A ', ' B ' ... a=97 a=65

Symbolic constants: Constants defined #define NUM 30 macros

(5) Variables

A person thinks that defining a variable is a container in memory that can change the contents of a container, but the container itself will not change.

For example, a variable of type int a,a can be either 1 or 2, but the address and type of a will not change.

Note: 1. Variables can only consist of letters, numbers, underscores, and the first character must be a letter or underline

2. Variables are case-sensitive, for example, int num and int num represent two variables

　　　

C Learning Notes (i) data, operators, expressions