Identifiers are the names that users use when programming. When we designate something or someone, we must use it, his or her name; When solving equations in mathematics, we often use variable names or function names of one kind or another. Similarly, in computer language, variables, constants, functions and sentence blocks also have names, which we all call identifiers.

As for the data types, operators, expressions and other components in C language, it is just like some data, operators and programs in mathematics when learning mathematics.

Integer, real number and character constant are written as follows:

# define int 1 = 123456； //Integer

# Define float1=123.123; //Real number type

# define str =' a// character type

Define variables: int I =1; //Integer

float j = 1. 1 1F； //Real number type

Char t =' a// character type

str 1 = " ABC "； //String

As for how to find the value of the expression, you can assign the value of the expression, or you can use the output function to directly output the value of the expression;

Evaluation rules are like evaluation rules in mathematics.