c - How to initialise array dynamically with a default value?

Question

I was initializing array (unsigned short int) of size 100000000 in C 4.3.2 , and other two int array of size 1000000. But while submiting on Online judge, it was giving SIGSEGV error .

Therefor i decided to initialize my array dynamically with a default value 0, as adding value by loop takes much time.

My question is how to initialise array dynamically with a default value ?

Answer 1

You can use void *calloc(size_t nmemb, size_t size); function to initialize memory with 0,

The calloc() function allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated memory. The memory is set to zero. If nmemb or size is 0, then calloc() returns either NULL, or a unique pointer value that can later be successfully passed to free().

 calloc(number of elements, sizeof(type));

or you can also use memset() explicitly to initialize memory allocated by malloc() call.

Note: calloc() isn't magic either - it will also use a loop somewhere to replace the garbage with all zeroes.

See also: Why malloc() + memset() is slower than calloc()?