[Courses] [C] Lesson12: Exercise answers

[Laura Bowser]

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>Is there any advantage for calloc over malloc or vice versa

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Slightly technical discussion follows:

calloc and malloc do *almost* the exact same thing.

the only difference is that calloc initializes the memory as well.  with 
malloc, your system may or may not initialize the memory. (Solaris doesn't, 
Linux does)

If malloc does initialize the memory for you, there is no advantage.

if malloc does not initialize the memory for you, then there is a *very* 
slight speed advantage to using malloc over calloc.  This is because there is 
code in calloc to initialize the memory.

if you need the memory initialized to 0 or NULL, then you're better off using 
calloc because it does some memory tricks (memset) to initialize the memory 
quickly (much more quickly than say a for loop).


Another issue that I used to tell my students was that calloc can be your 
friend because of it's different parameter list.  It helped the students 
remember that you need to give calloc a number of things to allocate, and the 
size of each of those things.  They would tend to forget this with malloc 
because it only takes one parameter.

Hope I cleared some of this up for you.  

Laura



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