C-Language Advanced day_01

Data type

1.1 Memory

Memory is linear and is addressable in bytes (8b)

1.2 Complement

Complementary features (reciprocal):

0 's complement is 0.

Sign BITS participate in the operation with ordinary bits

The complement can make subtraction into addition.

The range represented by 8-bit data ("128,127") is determined by the Code rules of the complement

Note:-1 (1111 1111)-128 (1000 0000) 127 (0111 1111)

1.3 Data Type Partitioning

Char 0-128 corresponds to the ASCII table

Why do I need data types?

The data type provides the size and access rules for the requested memory unit.

1.4 Type Conversions

1.4.1 Small data to big data

Bottom alignment/ symbol Auto-fill

Positive expansion 0/negative expansion 1

1.4.2 Big data to small data

int a=127;

Char b=a;

a=b=127;

int a=255;

Char b=a;

A=255;B=FFFFFFFF;

No data loss occurred above, only truncated

1.4.3-Implicit conversion

Plastic lifting: at machine, all lower than bits of shaping data-->32 bit shaping data.

Hybrid boost:

Complement + type conversion + symbol fill

Unsigned int fill 0000

The complement operation of Popular science:

The complement of positive numbers: Same as the original code

The complement of the negative number: The sign bit is 1, the remaining bits are the inverse of the original code of the absolute value, then the whole number is added 1.

Subtract from complement:

Subtraction:
Integer: [A] complement = [A] complement + [-b] Complement (mod 2^ (n+1))
Decimal: [A] complement = [A] complement + [-b] Complement (mod 2)

The [-b] complement, or [b] to complement, is to add one to each bit of the sign bit.

1.5 Memory Management

command-line arguments :

int main (int argc ( number of input data ) four bytes, char * argv[] ( input data ) 12 bytes )

1.6 Arrays

array Clear 0: int array "Ten "={0} ;--> The first data is set to 0 , followed by automatic initialization of 0 ;

Of course, arrays and two-dimensional arrays, pointers array There are many problems, I hope you can communicate a lot!!!

study next week, more C Language Improvement day_02 Thank You (* ^_^ *)

C-Language Advanced day_01