What is a safest way to set all bits of a variable to true in C?
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What is a safest way to set all bits of a variable to true in C?
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Re: What is a safest way to set all bits of a variable to true in C?
#2The next question: Why?
(To clarify: I mean, "why do you care what the bits are set to".)
Re: What is a safest way to set all bits of a variable to true in C?
#3The next question: Why? (To clarify: I mean, "why do you care what the bits are set to".)
Because it is defined as such? http://stackoverflow.com/questions/3100365/why-is-1-sizeofin...
Re: What is a safest way to set all bits of a variable to true in C?
#4The next question: Why? (To clarify: I mean, "why do you care what the bits are set to".)
Because of two's complement and the way implicit conversions work.
Re: What is a safest way to set all bits of a variable to true in C?
#5Re: What is a safest way to set all bits of a variable to true in C?
#6How many 'ones complement' machines exist?
Re: What is a safest way to set all bits of a variable to true in C?
#7Personally I'd use: unsigned int a = 0xFFFF, not unsigned int a = -1.
This is a classic case of a readability issue. 0xFFFF is, in my mind, much clearer on your intention than -1. The only problem is that you're assuming a specific int size, but really, if you're working with bits, chances are good that you're working on a platform where you know the architecture size (at least on embedded platforms).
Re: What is a safest way to set all bits of a variable to true in C?
#8Personally I'd use: unsigned int a = 0xFFFF, not unsigned int a = -1. This is a classic case of a readability issue. 0xFFFF is, in my mind, much clearer on your intention than -1. The only problem is that you're assuming a specific int size, but really, if you're working with bits, chances are good that you're working on a platform where you know the architecture size (at least on embedded platforms).
The problem is that you can't be sure how many bytes and int is on any given platform. So your way is more readable, but not portable.
Re: What is a safest way to set all bits of a variable to true in C?
#9Personally I'd use: unsigned int a = 0xFFFF, not unsigned int a = -1. This is a classic case of a readability issue. 0xFFFF is, in my mind, much clearer on your intention than -1. The only problem is that you're assuming a specific int size, but really, if you're working with bits, chances are good that you're working on a platform where you know the architecture size (at least on embedded platforms).
The problem is that you can't be sure how many bytes and int is on any given platform. So your way is more readable, but not portable.
[deleted]
Re: What is a safest way to set all bits of a variable to true in C?
#10Personally I'd use: unsigned int a = 0xFFFF, not unsigned int a = -1. This is a classic case of a readability issue. 0xFFFF is, in my mind, much clearer on your intention than -1. The only problem is that you're assuming a specific int size, but really, if you're working with bits, chances are good that you're working on a platform where you know the architecture size (at least on embedded platforms).
The problem is that you can't be sure how many bytes and int is on any given platform. So your way is more readable, but not portable.
Crap. This is why you don't respond without fully reading a comment. Where is my delete option? :-)