C language 01

1, in order to distinguish the octal system, the hexadecimal difference: eight before adding 0, hex plus x0, such as 058,x059;

2, binary conversion, binary, octal, decimal, hexadecimal conversion between each other. (converted to binary after the other is good conversion)

such as: decimal number 57, binary 111001, from binary to octal, from the right of the binary to the left 3 digits of a group, the front is not enough to fill 0, that is, 111,001, the calculation octal is 071;

Converted from binary to 16 binary, from the right of the binary to the left 4 digits of a group, the front is not enough to fill 0, that is, 0011,1001, the calculation of hexadecimal for 0x39;

3. Comments

Single-line Comment

/**/Multi-line comments

4. Basic data type

Commonly used are 3, char, int, float, respectively 1 characters, 4 characters, 4 or 8 characters; placeholder%c,%d,%f

5, variable, represents a storage area

Type modifier type name = initial value

6. Naming rules for variable names

Can only be made up of numbers, letters, and underscores, and numbers cannot begin

Cannot have the same name as a system reserved word

Cannot make a duplicate variable name.

See the name and the meaning (specification)

Hump nomenclature: The first letter is lowercase and the remaining initials are capitalized. such as: Studentage

7. Note: The return value of an expression

8. The statement is the smallest unit of program execution, ending with a semicolon

9, input, output statement

scanf if the reading data item type matches the format character, continue reading?; Otherwise, you are no longer viewing the remainder, which returns

Printf

10. Escape character

\ n Escape character

\ \ print \ printf ("\ \ \ n");

Percent Print% printf ("%%\n"); Output%

C language 01