How can you dynamically allocate memory using stack ( not heap )?
Do they need different functions than malloc(),calloc() ? Which header file is used?
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2 Answers
alloca(3) is the function you're looking for.
void test_alloca(int num)
{
int *myarray = alloca(num * sizeof(int));
// do not try to free(myarray) !
}
In C99 you can also declare a variable-length array:
void test_vla(int num)
{
int myarray[num];
}
These two code snippets are functionally identical. (An exception being that the first declares a pointer while the second declares an array, leading to different results if you take the sizeof(myarray).)
answered Jul 23, 2015 at 10:27
Jonathon Reinhart
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1 Comment
Ahtisham
Don't we need to do type casting in alloca ? and can't i declare variable length array when allocation is done on heap ? also i want to know why we need to allocate memory on stack for what reasons or can there be any situations where its must ??
The sentence in your question
dynamically allocate memory using stack
is a bit broad. However, In my opinion, you have two options,
But remember the fundamental difference, the lifetime of the allocated memory through aforesaid process will be limited by their scope.
