PHP original code, inverse code, complement code introduction_PHP tutorial

Introduction to PHP original code, inverse code, and complement code

PHP original code, inverse code, complement code introduction

Original code:

is the "original binary code", which is actually a character code that we can understand after converting from decimal to binary. The original codes are all numerically understandable. However, in the actual operation of the computer, the original code is often not used, so there are problems with the inverse code and the complement code.

Based on this, the rule: the first bit of a binary number is the sign bit, 0 represents a positive number, and 1 represents a negative number.

Example: (8 bits are used as examples):

7: 00000111

-7： 10000111

Reverse code:

The complement of a positive number is itself.

The one's complement of a negative number is to invert each bit of the non-sign part of the original code. .

Example:

7: 00000111

-7： 11111000

Complement code:

The complement of a positive number is itself

The one's complement of a negative number, the sign bit remains unchanged, after each other bit is inverted, the whole number is increased by 1

Example:

7: 00000111

-7: 11111000 1 = 11111001

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