c - Why must I cast the result from malloc?

The following code gives the error
"error: invalid conversion from void* to char* [-fpermissive]"

#include

#include
#include

int main(){
    char *t = malloc(20);
}

However, casting the result of malloc solves the problem. But I cannot understand why as this question says that casting the result of malloc is not needed.

Answer

You compiled this C program using a C++ compiler. It is necessary to cast the result of malloc in C++, but not in C.