Array static allocation

Question

int num = atoi(argv[1]);
unsigned long times[num];

I have this code and I assumed it won't compile because I am trying to allocate the array using a value from a command line argument, which compiler doesn't know at the compile time. But I compiled this code and it worked. Can someone explain what is going on here?? Am I misunderstanding the basic concept of static allocation??

essentially it's up to the compiler to determine a way of allocating the array at runtime, rather than at compile time. — obataku
– obataku, Commented Sep 5, 2012 at 5:44

Community · Accepted Answer · 2017-05-23 11:56:16Z

5

C99 allows to allocate an array with a var. This is called variable length arrays aka VLA

I don't have the C99 in my hand, the section is 6.7.5.2 in C99, and the following links are from the internet.

vla - wikipedia

c99 - wikipedia

be aware that vla is not supported in c++, more information here

edited May 23, 2017 at 11:56

CommunityBot

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answered Sep 5, 2012 at 5:39

shengy

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