While (~scanf ("%d", & n)) is equivalent to while (scanf ("%d", & n)! =eof)

【 Knowledge point 】
while(~scanf("%d", &n))    Equivalent to  while(scanf("%d",&n)!=EOF)
among ,~ yes According to the not .
If  scanf("%d", &n) Function successfully entered , Then return the number of input integers 1.1 Bitwise negation results in -2. by True.
If  scanf("%d", &n) Function has no input or input error , Then return to -1.-1 Bitwise negation results in 0.​​​​​​​ by False.

Understanding bitwise negation （~） The original code you need to know before 、 Inverse code 、 The complement rule ：
Data is stored in memory in the form of the complement of signed binary numbers . In the binary representation of signed integers , The highest bit is Sign bit （ The positive integer is 0, Negative integer is 1）, This is also the origin of signed integer names .
The original code of a positive number 、 Inverse code 、 The complement is the same .
The inverse of a negative number is equal to the sign bit of the original code , The rest of you take the opposite ; The complement of a negative number is the inverse plus 1.

Examples of bitwise negation operations are as follows ：

 negative ：-1
 Original code ：1000 0001
 Inverse code ：1111 1110 （ The sign bits remain the same ）
 Complement code ：1111 1111 （ The sign bits remain the same ）

 According to the not ：0000 0000 （ The sign bit is also reversed ）
 Because the sign bit is 0, Is a positive number . Therefore, complement is equal to the value after bitwise inversion  0000 0000, Its decimal system is 0. That is to say -(-1+1)=0

-------------------------------------

 negative ：-10
 Original code ：1000 1010
 Inverse code ：1111 0101 （ The sign bits remain the same ）
 Complement code ：1111 0110 （ The sign bits remain the same ）

 According to the not ：0000 1001 （ The sign bit is also reversed ）
 Because the sign bit is 0, Is a positive number . Therefore, complement is equal to the value after bitwise inversion  1111 0110, Its decimal system is 9. That is to say -(-10+1)=9

=============================================================================

 Positive numbers ：1
 Original code ：0000 0001
 Inverse code ：0000 0001 （ The sign bits remain the same ）
 Complement code ：0000 0001 （ The sign bits remain the same ）

 According to the not ：1111 1110 （ The sign bit is also reversed ）
 Because the sign bit is 1, It's a negative number . There are ：
 Original code ：1111 1110
 Inverse code ：1000 0001 （ The sign bits remain the same ）
 Complement code ：1000 0010 （ The sign bits remain the same ）

 Therefore, the decimal system corresponding to the complement is -2. That is to say -(1+1)=-2

-------------------------------------

 Positive numbers ：10
 Original code ：0000 1010
 Inverse code ：0000 1010 （ The sign bits remain the same ）
 Complement code ：0000 1010 （ The sign bits remain the same ）

 According to the not ：1111 0101 （ The sign bit is also reversed ）
 Because the sign bit is 1, It's a negative number . There are ：
 Original code ：1111 0101
 Inverse code ：1000 1010 （ The sign bits remain the same ）
 Complement code ：1000 1011 （ The sign bits remain the same ）

 Therefore, the decimal system corresponding to the complement is -11. That is to say -(10+1)=-11

0 Not a positive number , It's not a negative number . But the operation rule of bitwise negation is the same as above .

 Integers ：0
 Original code ：0000 0000
 Inverse code ：0000 0000 （ The sign bits remain the same ）
 Complement code ：0000 0000 （ The sign bits remain the same ）

 According to the not ：1111 1111 （ The sign bit is also reversed ）
 Because the sign bit is 1, It's a negative number . There are ：
 Original code ：1111 1111
 Inverse code ：1000 0000 （ The sign bits remain the same ）
 Complement code ：1000 0001 （ The sign bits remain the same ）

 Therefore, the decimal system corresponding to the complement is -1. That is to say -(0+1)=-1

Sum up ：
Integers a According to the not （~） The value after is -(a+1)​​​​​​​



【 reference 】
https://blog.csdn.net/hnjzsyjyj/article/details/119720322
https://blog.csdn.net/hnjzsyjyj/article/details/120794381
https://blog.csdn.net/qq_34681580/article/details/115248595