static object initialization every time function is called

Question

I have a pretty heavy object in my code which is static. I was wondering if you move the initialization of the member variables outside of the constructor, would they execute every time or just once?

struct test
{
    int a;
    int b;
};
void foo() {

    static test T;
    T.a=123;
    T.b=341;

}

int main()
{
    foo();
    foo();
    foo();
}

Will

T.a=123;
T.b=341;

be executed every time foo() is called?

Swift - Friday Pie · Accepted Answer · 2020-04-02 11:14:48Z

1

that's not initialization, that's assignments, and yes, it will. Only creation of object (including initialization) happens once.

static test T = {123,341}; //happens only once.

or any other appropriate initialization, as long as all assignments or initializations are done in constructor body.

edited Apr 2, 2020 at 11:14

answered Apr 2, 2020 at 11:03

Swift - Friday Pie

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7 Comments

A.Hristov Over a year ago

Unfortunately for my project this throws could not convert ... from <brace-enclosed initializer list>. This stems from the fact that I do not have c++17 support( c++17 is not an option for this project).

Swift - Friday Pie Over a year ago

@A.Hristov pardon me, that's C++98 for this particular case, C++11 in general case. You have some different declaration of actual structure, e.g. a constructor present. DO appropriate initialization ,

melk Over a year ago

I don't think the error has anything to do with missing c++17-support, but stems form the fact that you haven't declared a constructor for test (one like this: test(int _a, int _b) : a(_a), b(_b) {}

Swift - Friday Pie Over a year ago

@melk likely he got any other constructor present. this syntax ( assignment-style initialization with braced initializer) works with trivial structures since 98. In C++11 it is re-classified into initialize list. It won't work in any standard if he got a ctor.

melk Over a year ago

@swift Wouldn't not declaring a constructor result in the default-constructor being created, which doesn't take any arguments, and thus wouldn't work with an initializer-list?

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