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c program to set the m-bit to n-bit

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# 1  
Old 02-24-2012
c program to set the m-bit to n-bit
I have a 32bit number and without using for loop,I want to set mbit to n bit.

Say m bit may be 2nd or 5th or 9th or 10th.n bit may be 22nd or 27or 11th bit.

I assume m<n.

Please help me.Thanks

acdc
# 2  
Old 02-24-2012
It is going to be easy if you write down the steps...pseudocode it etc.
# 3  
Old 02-24-2012
if(X & (1<<M)) X = (X&~(1<<M)) | (1<<N);
# 4  
Old 02-24-2012
Quote:
Originally Posted by Corona688
if(X & (1<<M)) X = (X&~(1<<M)) | (1<<N);
Even shorter...Smilie
Code:
num ^= (1<<m | 1<<n);

# 5  
Old 02-24-2012
That will flip bit N and bit M, not set them. It will also do so no matter what their states are -- it could as easily turn off bit N as on...
This User Gave Thanks to Corona688 For This Post:
shamrock
# 6  
Old 02-24-2012
Quote:
Originally Posted by Corona688
That will flip bit N and bit M, not set them. It will also do so no matter what their states are -- it could as easily turn off bit N as on...
My bad...I had skimmed the post and thought the op wanted bit m and bit n swapped.
# 7  
Old 02-25-2012
Quote:
Originally Posted by acdc
I have a 32bit number and without using for loop, I want to set mbit to n bit.
...
I assume m<n.
I don't think anyone understood your question, since the suggestions proffered do not reflect what I consider to be the two likeliest interpretations.

Are you trying to set the value of the bit at index m equal to the value of the bit at index n? Or are you trying to set all bits from index m to index n to 1? Or something else entirely?

Why are you not able to use a for loop?

Regards,
Alister
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