1, C language-basic knowledge

Basic knowledge

First, the numbering and conversion
1. Four systems: binary decimal octal hexadecimal
1) Decimal Definition
0 1 2 3 ... 90 Coding Symbols
Every ten in a
2) binary definition
0 12 Coding Symbols
Every two in one
3) Octal definition
0 1 2 3 ... 78 Coding Symbols
Every eight in a
4) Hex Definition
0 1...9 a B C D E F 16 Coding symbols
Every 16 in one
2. The four types of the two-way conversion
1) 10--Binary
Formula: In addition to 2 of the surplus inverted row
2) Two--Decimal
Formula: Add by the right of bitwise multiplication
3) Two--octal
Formula: Three positions pressed into one
Eight-to-two binary
Formula: One press into three bits
4) Two-hex
Formula: Four positions pressed into one
Binary, 16
Formula: One press into four bits

Second, the application of the numeral
1, ASCII code-the only binary code??
2. Memory
3. Machine code
4. Address mapping
5. IP Address

1, C language-basic knowledge