Data types, variables, and operators

One. Data type

int shaping such as:, etc.;

Double dual precision floating point type such as: 2.3, 3.4, etc.;

string strings such as: "", "good", etc.;

Char character type such as: ' Number ', ' male ', etc.;

The Boolean Boolean type has only two values of--false/tyue;

Two. Variable

1. Variable definition: Allocate a space in the memory space to store the data;

2. Structure of variables: data type, variable name, value of variable;

3. Syntax for declaring variables: data type variable name; nit num;;

4. Syntax for assigning a variable: variable name = value; num=3;;

5. The syntax of the life variable and assignment: The data type variable name = value, such as: int num=3; ;

6. Naming conventions for variable names:

1. Variable names cannot contain Java keywords;

2. The variable name must begin with a letter, an underscore "_", "$";

3. Variable names can contain numbers but cannot start with numbers;

4. The first word of the variable name is lowercase followed by a special meaning of the first letter of the word capital;

5. The name of the variable names should be meaningful, as far as possible with a short English word name;

Three. Operators

1. Arithmetic operators

1.+ addition operator;

2.-subtraction operator;

3./rounding operator;

4.% the remainder operator;

5.* multiplication operator;

2. Relational operators

1.< indicates that one operand is less than the other;

2.< indicates that one operand is greater than the other operand;

3.<= indicates that one operand is less than or equal to another operand;

4.>= indicates that one operand is greater than or equal to another operand;

5.== indicates that one operand equals another operand;

3. Logical operators

1.&& logic and truth are true, the rest is false

2.| | The logic or the truth must be true, the rest is false

3.! = Logic is not true, its false is true

4. Assignment operators

The 1.= assignment operator assigns the value on the right side of the equal sign to the variable on the left

Data types, variables, and operators