1, integer constant

In C language, integer constants are divided into decimal integer constants, octal integer constants and hexadecimal integer constants.

The above three binary constants can be used in different situations. Decimal constants are used in most cases, but when writing system programs, such as indicating addresses, octal or hexadecimal constants are often used.

Generally speaking, the compiler will distinguish whether a constant is an int type or a long int type according to its numerical value.

2. Real constant

There are two representations of real constants: one is decimal form, and the other is exponential form.