C Foundation--Constant variable note

Program Compile link principle
Preprocessing:. C. i
GCC-E Hello.c-o hello.i

Compiling:. I/. C. S
Gcc-s Hello.i-o Hello.s

Compilation:. S. o
Gcc-c Hello.s-o hello.o

Link:. O-Executable app
GCC Hello.o-o App

Gedit hello.c

Small-end storage Method-high address memory high byte, low address low memory byte (survivable high, low save low)
(Intel/arm)
0x indicates hexadecimal

Value: 0x12 34 56 78 How to store in small-end memory

0x80030x12
0x80020x34
0x80010x56
0x8000 0x78

1 BYTE = 8bit

Big-endian storage Method--high address memory low byte, low address memory high byte (survivable low, low storage height)
(IBM mainframe/network byte order)
Value: 0x12 34 56 78 How to store in small-end memory

0x80030x78
0x80020x56
0x80010x34
0x8000 0x12

Binary conversion
10 Binary: 0,1,2,3,4,5,6,7,8,9,10
2 binary: 0,1
8 binary: 0,1,2,3,4,5,6,7
16 Binary: 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f

Bashing
1 2 3

1x10^2 + 2x10^1 + 3x10^0

0 1 0
0x2^2 + 1x2^1 + 0x2^0 = 2

1100 1010
0+2+0+8+64+128=202

Binary: 000 001 010 011 100 101 110 111 001000
Decimal: 01 2 3 4 5 6 7 8
Octal: 01 2 3 4 5 6 7 10

binary: 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
Decimal: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Hex: 0 1 2 3 4 5 6 7 8 9 A B C D E F

Binary: 1010 0001 1000
Hex: A 1 8

Hex: 3d7
Binary: 0011 1101 0111

Octal: 11
Binary: 001 001

37
Octal Start: 0
Hex Start: 0x
Decimal start: Nothing to do with

Octal: 0777
Hex: 0xffff8000

5 binary: 3x5^0 + 2x5^1 = 13

8 4 2 1

2^3 2^2 2^1 2^0

1000 0100 0010 0001

0111

Decimal: 89 corresponds to binary 1011001
89 ..... 1
44 ..... 0
22 ..... 0
11 ..... 1
5 ..... 1
2 ..... 0
1 ..... 1

1011001
1+0+0+8+16+0+64 = 89

49 ... 1
24 ... 0
12 ... 0
6 ... 0
3 ... 1
1 ... 1

0011 0001
0x31

0567
101 110 111

Bit bits

8bit = 1BYTE = "Each byte has an address

0x8003
0x8002
0x8001
0x8000

1 and-1

Original code anti-code complement

10000 00010000 00010000 0001 positive Inverse code, complement is equal to the original code
-11000 00011111 11101111 1111 The complement of negative numbers equals the inverse code plus 1.

00000 00000000 00000000 0000
-01000 00001111 11110000 0000

if (0 equals-0)
Execute AAAA;
Otherwise
implementation of BBBB;

97 = "97 ... 1 = 0110 0001
48 ... 0
24 ... 0
12 ..... 0
6 ... 0
3 ... 1
1 ... 1
Original code anti-code complement
-31 = = 31 ... 1 = 0001 1111 = 1001 1111 = 1110 0000 = 1110 0001
15 ... 1
7 ... 1
3 ... 1
1 ... 1

char B = 1; = ( -128~127)
unsigned char a = 129; = (0~255)
S
0000 0000
1000 0001
1111 1111
Int
unsigned int (0~2^32-1)

Char b = ' x ';
int c = 10;

' x ' = 0111 1000
Ten-1010
.
.
.
0x8003
0x8002
0x8001
&b = 0x8000 1BYTE 0111 1000
.
.
.
0x70030000 0000=>0x00
0x70020000 0000=>0x00
0x70010000 0000=>0x00
&c =>0x7000 0000 1010=>0x0a
printf ("&c =%p\tc =%d", &c, C);

' X ' = 120
' \a '
‘"‘
345

"Hello" = "h" E "L" ' O "

' a ' = = ' a '
"A" = "C";

"123" = 123

' 1 ' 2 ' 3 '

' 1 '-' 0 ' = 1
1*10 + ' 2 '-' 0 ' = 12
12*10 + ' 3 '-' 0 ' = 123

int a = 5;
A% 3 = 2
A/2 = 2

Float A = 5.0
A% 3 =??? Error
A/2 = 2.5

1. Print basic data type sizeof size
2. Use vs2013 to see the memory and see the values in the address and address of the variable.

C Foundation--Constant variable note