School assignment

[DrCake]

Hi,

If got a C++ assignment for school, but im stuck :(

This is assignment:

#include <iostream> 
using namespace std; 
const short bit0 = 0; 
const short bit1 = 1; 
const short bit2 = 2; 
const short bit3 = 3; 
const short bit4 = 4; 
const short bit5 = 5; 
const short bit6 = 6; 
const short bit7 = 7; 
int main(){ 
 unsigned char p1 = 0xA0;                                   
 unsigned char p2 = 0x3F; 
 cout << "p1 en p2 have the value:" << endl; 
 // set output to hex mode 
 cout << (short)p1 << '\t' << (short)p2 << endl;            
 //setting of bit 2 in a byte: 
 p1 = p1 | (1<<bit2); 
 //resetting of bit 4 in a byte: 
 p2 = p2 & ~(1<<bit4); 
 cout<<"p1 en p2 have after the editing the value:"<< endl; 
 cout << (short)p1 << '\t' << (short)p2 << endl; 
 system("PAUSE"); 
 return 0; 
}

and we need to do this:
Set bit2 of p1, and reset bit7

Please help me :(

Greetings

[Blessman11]

could you translate a bit, it would make it a bit clearer

[DrCake]

Translated it now

[john2]

p1 = p1 | (1<<bit2);       //set bit2 of p1, 
p1 = p1 & ~(1<<bit7);      //reset bit7 of p1. 

[DrCake]

@John2,
Could you explain it to me? i dont get anything of the assignment :(

[john2]

<< is a bitwise operator. It shifts the bit in a byte to the left, compared to >> which shifts them to the right:

1<<bit2 = 1<< 2 ofcourse cause bit2 is declared to be 2.
1 = 00000001 in byte form.
Now the operation:

00000001 <<
00000100 You can see it 'shifts' the bit to the left two places.

Now for: p1 = p1 | (1<<bit2);

p1 = 0xA0 = 160 = 10100000
10100000
00000100 | (the or operator)
10100100 = 164

Now for: p2 = p2 & ~(1<<bit4);

p2 = 0x3F = 63 = 00111111
1<<bit4 = 1<<4 = 00010000
00010000 ~ (bitwise not operator)
11101111

00111111
11101111 & (bitwise and operator)
00101111 = 47