How can I compare char and int with bitwise operators in C++ ?

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how can i compare char and int with bitwise operators in c++ ?I can't understand that when i enter A,output will be small a.Why?Actually,what does "comparing of int number 32 and character" mean?how can i reach that result?If someone know this,please let me know also :) Another question ,is it possible use & or ^(exclusive or) to compare them?

C++

#include<iostream>
using namespace std;
int main()
{
	int t=32;
	char ch;
	cout<<"Enter a capital letter:";
	cin>>ch;
	ch=(ch|t);
	cout<<ch<<endl;
	return 0;
}

What I have tried:

I have searched about this,but i can't find answer which is related bitwise operator.

Posted 11-Sep-16 6:21am

Member 12702056

Updated 11-Sep-16 7:10am

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3 solutions

Solution 3

Your code doesn't "compare" anything: it read a character from the user, makes sure that a specific bit is to one - from the value 32 you are Binary ORing the character with - and outputting it.
Since the decimal value 32 is hex 20, and teh difference between "A" and "a" is one bit: http://www.asciitable.com/index/asciifull.gif[^] the OR will ensure that the character it output is always lower case. Unless it's character in this set: "@[\]^" which get converted to "`{|}~" and "_" which will be font dependant.

And no, & (AND) and ^ (XOR) do not do comparisons either. To compare anything, you need to use a conditional instruction like if or while for example.

Posted 11-Sep-16 7:10am

OriginalGriff

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Member 12702056 11-Sep-16 14:25pm

Thanks for your answer,but actually you explained in the difficult way for me :)
Especially this part:"the OR will ensure that the character it output is always lower case. Unless it's character in this set: "@[\]^" which get converted to "`{|}~" and "_" which will be font dependant."

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Richard MacCutchan · Accepted Answer · 2016-09-11T07:04:00

Solution 2

"A" is hex 0x41
32 is hex 0x20
0x41 | 0x20 is 0x61 which is "a"

I have no idea what you are trying to achieve, perhaps you should edit your question.

Posted 11-Sep-16 7:04am

Richard MacCutchan

Comments

Member 12702056 11-Sep-16 14:26pm

Thank you,i got what i tried to understand :)

Patrice T · Accepted Answer · 2016-09-11T07:04:00

Quote:
I can't understand that when i enter A,output will be small a.Why?

Use the debugger to see what happen in your code.

You should learn to use the debugger as soon as possible. Rather than guessing what your code is doing, It is time to see your code executing and ensuring that it does what you expect.

The debugger allow you to follow the execution line by line, inspect variables and you will see that there is a point where it stop doing what you expect.
Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.

For your actual problem:
A is ASCII code 65 and a is ASCII code 97: difference is 32.
ASCII - Wikipedia, the free encyclopedia[^]
Tutorials - Bitwise Operators and Bit Manipulations in C and C++ - Cprogramming.com[^]

Quote:
Another question ,is it possible use & or ^(exclusive or) to compare them?

It is not the general usage, but yes, it is possible, but everything depend on what kind of comparison you want to do.

[Update]

Quote:
But if i compare char and int ,must i change one of them to another one type?like,if i compare x is greater or 4 ,must i change x to int,or 4 to char?

Looks like you need to learn C/C++ properly
Here is links to references books on C and C++ by the authors of the languages. Note than C is the ancestor of C++, so knowing C is always useful with C++.
The C Programming Language - Wikipedia, the free encyclopedia[^]
https://hassanolity.files.wordpress.com/2013/11/the_c_programming_language_2.pdf[^]
http://www.ime.usp.br/~pf/Kernighan-Ritchie/C-Programming-Ebook.pdf[^]

C++ Programing Language[^]