malloc error: a value of type "void *" cannot be used to initialize an entity of type "int **"

Question

I have tried:

int** thread_args = malloc(24);

and

int** thread_args = malloc(sizeof(int*) * 3);

but I keep getting the error message.

I would really appreciate your help!

Possible duplicate of [invalid conversion from \*void to \*int \[-fpermissive\] using malloc(sizeof())](https://stackoverflow.com/questions/34286287/invalid-conversion-from-void-to-int-fpermissive-using-mallocsizeof) — Gaurav Pathak, Sep 17 '18 at 07:31
@tkausl yes. I am new to C++, and I never used to get this error in C99 — CottonCandy, Sep 17 '18 at 07:32
Well you should tag C++ then, not C. This is valid in C but not in C++. You have to decide which language you want to program in. — tkausl, Sep 17 '18 at 07:33
Possible duplicate of [Why does C++ require a cast for malloc() but C doesn't?](https://stackoverflow.com/questions/3477741/why-does-c-require-a-cast-for-malloc-but-c-doesnt) — melpomene, Sep 17 '18 at 07:38
@Isaac See Wikipedia article [Compatibility of C and C++](https://en.wikipedia.org/wiki/Compatibility_of_C_and_C%2B%2B) — HostileFork says dont trust SE, Sep 17 '18 at 07:38
You forgot to try `int** thread_args = new int*[3];`, which is the C++ way. Next stop on the C++ train: `std::vector> thread_args(3);`. — molbdnilo, Sep 17 '18 at 07:47

score 10 · Accepted Answer · answered Sep 17 '18 at 07:39

10

If you use C++ compiler, you may need to cast the result of malloc:

int ** th_args = (int**)malloc(24)

or simply use operator new.

If you use a C compiler, then... I am not sure of why this error is thrown

answered Sep 17 '18 at 07:39

PhoenixBlue

1

I'm pretty sure you're supposed to use `static_cast<>` in C++ (or an existing container type, really). – melpomene Sep 17 '18 at 07:48

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