Difference between C and C++ static initialization [duplicate]

Question

When compiling this code sample

#include <stdio.h>
#include <stdlib.h>

int myfunc()
{
    printf("Constructor\n");
    return 1;
}

static const int dummy = myfunc();

int main()
{
    printf("main\n");
    return 0;
}

it works when compiled as C++, but not as C using the same compiler (MingW gcc). I get an initializer element is not constant in C mode.

So apparently there are differences regarding static intialization. Is there a reason why this is apparently allowed for C++ but not for C? Is this because otherwise you wouldn't be able to have global objects with constructor functions?

Answer 1

C++ compiler generates an additional 'Start' function, where all "global function calls" are executed before the PC (program counter) is set to the address of 'main'.

A "global function call" is any function-call which is performed in order to initialize a global object (including implicit function calls, i.e., constructors).

C compiler does not generate such 'Start' function, and the PC is set to 'main' as soon as the OS loads the executable and runs the process.