<< Dark Horse programmer >> Basic Arithmetic

The C language provides a total of 34 operators

Arithmetic operations

1 addition operation +.

2 addition operation-.

3 multiplication Operation X.

4 Division operation/.

5 residual operation%.

① the remainder after dividing two integers

②% can only be integers on both sides

③ positive and negative depending on% left value

Type conversions

Automatic type conversion

int a = 10.5;//will convert 10.5 to int type;

Forcing type conversions

int a = (int) 10.5; Now convert 10.5 to int type, assign a value to A;

Self-increment operation

+ + is a self-increment operator,

++a; indicates that the value of a is first used in addition one;

a++; means first to a plus one, in use a;

Use of sizeof

Used to calculate the number of bytes of memory occupied by a variable, a constant, and a data type;

Basic form

sizeof (variable/constant)

sizeof variable/constant

sizeof (data type)

sizeof data type This writing format is incorrect

Relational operations

>, >=, <, <=,! =;

The result of the relational operation is a total of two

① condition is established as true, the result is 1;

② condition is not established as false, the result is 0;

Note the point:

C language provisions, any value is true and false, not 0 of the value is true, only 0 is false;

Priority level

The precedence of = =,! = In the relational operator is equal;

The priority of <, <=, >, >= is equal, and the priority of the former is lower than the latter: 2==3>1

The associative direction of the relational operator is "left to right": 4>3>2

The precedence of the relational operator is less than the arithmetic operator: 3+4>8-2

Logic operations: &&, | | 、！

① conditions 1 && conditions 2

When condition 1 and condition 2 are true, the result is only 1;

When condition 1 is true, when condition 2 is false, the result is 0;

When the condition 1 is false, it is not necessary to judge whether the condition 2 is true or FALSE, the result is 0;

The combination of logic and direction is "from left to right";

② Condition 1 | | Condition 2

When condition 1 and condition 2 have only one to be true, the result is 1, which is true;

When condition 1 is true, it is not necessary to judge whether the condition 2 is true, and the result is 1;

When the condition 1 is false, judging whether the condition 2 is true, if the condition 2 is true, the result is 1, if the condition condition 2 is false, the result is 0;

The logical or binding direction is "from left to right".

③! Condition 1

If condition 1 is established, the result is 0;

If condition 1 is not established, the result is false;

Is true change false, false change true;

The logical non-union direction is "from right to left".

Trinocular operator

Conditions? Value 1: Value 2

int a = ten > 5? A:b

If the condition of > 5 is established and returns a, b if the condition is not established;

<< Dark Horse programmer >> Basic Arithmetic