如何将一个数组值合并为一个整数 C++

Question

如何将一个数组值合并为一个整数并颠倒？

example: a[]=0b1011,0b1111 to 10111111 and 10010101 to b[]=0b1001,0b0101

Answer 1

You need to covert types so that the values so they can hold 8 bits (a char or uint8 would do depending on what you need). I'm not sure what type you have there as its 4 bits. You're better off redefining the type to be a uint8 or something so a[0] = 0b00001011.

Once you have the right number of bits need to bitshift the first value left by 4, then use the bitwise OR operator, taking your example,

int8 myValue = a[0] << 4 | a[1]

Here's whats going on

• Bitshift: a[0] << 4 means move every bit to the left 4 times so 0b00001011 becomes 0b10110000 (bits coming into the right default as 0)

• Bitwise OR: a[0] << 4 | a[1], the | compares every bit from a[0] with a[1]. If either on of the bits are 1's it gives a 1, if both are 0, it gives a 0 ie

  10110000 | 00001111 = 10111111

By upside down I assume you mean in reverse?

You'll need to use the bitwise AND &, and do something similar so I wont explain in detail again, but its this

a[0] = (myValue & 0b1111000) >> 4 = 00001011

a[1] = myValue & 0b00001111 = 00001111

Hope that helps.

Answer 2

<< and | to "paste" two integers together, >> and & to take them apart.

For instance, (3 << 4) | 5 (3 << 4) | 5 is 53, 53 >> 4 is 3, 53 & 7 is 5.
(Translating the integers to binary notation left as an exercise.)

Answer 3

tnq for help,i want a code to do this

a[]={1,2,3,5,8,6,7,4};
result=a[0,1,2,3]+a[4,5,6,7];
result-->9909