Trouble with bitwise logic operations

[neevor]

I am new to c++ and have had no problems until i got to bitwise logic operations. I compiled the code from a book i have and i can't get it to work right. I can get it to take in two variables but it won't treat them like hex numbers. If i enter someting like 00ff as an argument it won't work. If you can help me thank you very much.
#include <stdio.h>
#include <iostream.h>
int main(int nArg, char* nArgs[])
{
    //set output format to hexadecimal
    cout.setf(ios::hex);
    
    //input the first argument
    int nArg1;
    cout << &quot;Enter arg1 as a four-digit hexadecimal: &quot;;
    cin >> nArg1;
    
    int nArg2;
    cout << &quot;Enter arg2: &quot;;
    cin >> nArg2;
    
    cout << &quot;nArg1 & nArg2 = 0x&quot;
            << (nArg1 & nArg2) << &quot;\n&quot;;
            
    cout << &quot;nArg1 | nArg2 = 0x&quot;
            << (nArg1 | nArg2) << &quot;\n&quot;;
    cout << &quot;nArg1 ^ nArg2 = 0x&quot;
            << (nArg1 ^ nArg2) << &quot;\n&quot;;
            
    return 0;
}

 

[newmangj]

I suspect the problem only occurs when you enter an argument with a-f included, when arg1 & arg2 contain only numeric digits it works OK,

You are trying to enter non-numeric data into an integer - this would appear to be where your problem lies.

Cheers

 

[neevor]

thanks,
do you know how to make a variable accept hexadecimal integers

 

[newmangj]

You would have to read it in as a string, convert it into an integer, do the bitwise math then convert the integer result back to hex for the output phase....

 

[neevor]

ok, thanks,
do you know why this code works with Visual C++ on windows,
but not on freebsd? I was wondering what the compiler diffrences were.

 

[newmangj]

Unfortunately I can't help you there, I have Windows (2000, NT & 95), Linux (various), Solaris (7 & 8) , AIX 4.3.3 and OS/390 to play with but not FreeBSD - sorry.

 

[neevor]

I have mandrake linux and i can't get it to work on that either.

 

[xwb]

To input a hex number add in the word hex. eg

cin >> hex >> nArg1;

iostream.h is the old version. You should really be using iostream.

#include <iostream>
using namespace std;
int main()
{
//set output format to hexadecimal
cout.setf(ios::hex);

//input the first argument
int nArg1;
cout << &quot;Enter arg1 as a four-digit hexadecimal: &quot;;
cin >> hex >> nArg1;

int nArg2;
cout << &quot;Enter arg2: &quot;;
cin >> hex >> nArg2;

cout << &quot;nArg1 & nArg2 = 0x&quot;
<< (nArg1 & nArg2) << &quot;\n&quot;;

cout << &quot;nArg1 | nArg2 = 0x&quot;
<< (nArg1 | nArg2) << &quot;\n&quot;;
cout << &quot;nArg1 ^ nArg2 = 0x&quot;
<< (nArg1 ^ nArg2) << &quot;\n&quot;;

return 0;
}

 

[neevor]

Thank you, this solved the problem of it not taking the hex numbers, but it is giving me the wrong answers?
The first answer for the set
nArg1 = 0x1234
nArg2 = 0x00ff
should be
0x34
i am getting
0x52

 

[newmangj]

You need to modify the output statements to format the output in hex, you are currently showing them as decimal values...

Try these changes and it should now work.

cout << &quot;nArg1 & nArg2 = 0x&quot;
<< hex << (nArg1 & nArg2) << &quot;\n&quot;;
cout << &quot;nArg1 | nArg2 = 0x&quot;
<< hex << (nArg1 | nArg2) << &quot;\n&quot;;
cout << &quot;nArg1 ^ nArg2 = 0x&quot;
<< hex << (nArg1 ^ nArg2) << &quot;\n&quot;;

Cheers - Gavin

 

[neevor]

Yeeahh!!
Worked perfect,
thank you very much.