C language bit operation - learning 26

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Operator

• Instructions :
  • 1. Bit operator , except Bitwise negation operator “~” Outside , Others are Two eyes ( element ) Operator , That is, there is an operation object on both sides of the operator ;
  • 2. Bitwise The data type of the operand Can only be integer or Character ;
  • 3. Bit operations can be combined with assignment operators , Composition bit compound assignment operator : <<=、=>>、 &=、 ^=、|=

Bitwise negation

• Grammar format ：
  • ~ expression
• Bitwise negation operator （~） The operation rules of ： The value of the expression participating in the operation is bitwise “ Inverse ” operation . That is to say, on each binary bit of the expression value 1 Turn into 0,0 Turn into 1.
• According to the not （~） by Monocular operator , Its The priority is the same as that of other unary operators , And at the same level From right to left combination .
• for example ：int a=1;~a namely
  • 00000001 -----------------------------------
  • 11111110, therefore ~a It's worth it -2 .
• Example

#include <stdio.h>

void main(){
    short int a = 1, b;
    b = ~a;
    printf("a= %d\nb= %d\n",a, b);
}

Bitwise and operation

• Grammar format ：
  • expression 1 & expression 2
• Bitwise and operator （&） The operation rules of ： Carry out the two expression values participating in the operation according to the corresponding hexadecimal digits “ And ” operation . The two corresponding binary bits are 1 when , The result of this bit is 1; Otherwise 0.
• for example ：3 & 5 namely
  • 0000 0011
  • 0000 0101 -----------------
  • 0000 0001, therefore 3&5 It's worth it 1.
• Be careful ： Negative numbers take part in the bitwise sum operation in the form of complement .
• Use “ Bitwise AND （&）” Operator , Pay attention to “ Logic and （&&）” Operator differences .
• Example

#include <stdio.h>

void main(){
    short int a = 3, b=5,c;
    c= a & b;
    printf("c= %d\n",c);
}

Bitwise OR operation

• Grammar format ：
  • expression 1 | expression 2
• bitwise or operator （|） The operation rules of ： Carry out the two expression values involved in the operation according to the corresponding binary “ or ” operation . When two corresponding binary bits have 1 Is it 1 when , The result of this bit is 1; Otherwise 0.
• for example ：3 | 5 namely
  • 0000 0011
  • 0000 0101 -----------------
  • 0000 0111, therefore 3|5 It's worth it 7.
• Be careful ： Negative numbers take part in the bitwise sum operation in the form of complement .
• Use “ Press bit or （|）” Operator , Pay attention to “ Logic or （||）” Operator differences .
• Example

#include <stdio.h>

void main(){
    short int a = 3, b=5,c;
    c= a | b;
    printf("c= %d\n",c);
}

Bitwise exclusive or operation

• Grammar format :
  • expression 1 ^ expression 2
• bitwise exclusive or operator （^） The operation rules of ： Carry out the two expression values involved in the operation according to the corresponding binary bits “ Exclusive or ” operation . When two corresponding binary bit values are different, it is 1; Otherwise 0.
• for example ：3 ^ 5 namely
  • 0000 0011
  • 0000 0101 -----------------
  • 0000 0110, therefore 3^5 It's worth it 6.
• Example

#include <stdio.h>

void main(){
    short int a = 3, b=5,c;
    c= a ^ b;
    printf("c= %d\n",c);
}

Move left

• Grammar format :
  • expression 1 << expression 2
  • expression 1 Is the moved operand
  • expression 2 Is the number of bits moved
• Shift left operator （<<） The operation rules of ： Expression 1 The binary bits of the value of each left shift expression 2 Number of digits of the value of . When the binary bit moves to the left , The removed high bits are discarded directly , The vacancy in the low position is filled 0.
• for example ：int a=1;a << 2 namely
  • a=0000 0001
  • a=0000 0100 therefore a << 2 It's worth it 4.

- Example

#include <stdio.h>

void main() {
    int a = 1,b;
    b = a << 2;
    printf("b= %d\n", b);
}

Move right

• Grammar format :
  • expression 1 >> expression 2
  • expression 1 Is the moved operand
  • expression 2 Is the number of bits moved
• Fill the space on the left after moving to the right 0 Or make up 1 And the expression 1 The type of and the machine used are related to the compilation environment
• Shift right operator （>>） The operation rules of ： Expression 1 The binary bit of the value of each shift right expression 2 Number of digits of the value of . When the binary bit moves to the right , Positive left to fill 0, Negative numbers are usually left complemented 1, On the right side of the discarded ( That is, do not change the original numerical symbol ).
• If it is an unsigned type , When the binary bit moves to the right, the left complement 0, On the right side of the discarded .
• Move right n Bits are equal to dividing by 2n
• Be careful ： The original symbol is 1( negative ), There is a vacancy on the left 0 still 1, Depends on the computer system used , Some systems supplement 0, Some systems supplement 1. repair 0 Of is called “ Logical shift right ”, Also known as simple shift right ; repair 1 It is called a “ Arithmetic shift right ”
• for example ：int a=4;a >> 2 namely
  • a=0000 0100
  • a=0000 0001 therefore a >> 2 It's worth it 1.
• for example ：int a=-4;a >> 2 namely

- Example

#include <stdio.h>

void main() {
    int a = 4,b;
    b = a >> 2;
    printf("b= %d\n", b);
}

Bit assignment operation

• Bit operation can be combined with assignment operation to form bit operation assignment operator .
  • &= example ：a&=b amount to a=a&b
  • |= example ：a|=b amount to a=a|b
  • >>= example ：a>>=b amount to a=a>>b
  • <<= example ：a<<=b amount to a=a<<b
  • ^= example ：a^=b amount to a=a^b