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c++double

Difference Between Double's Notation

On the learncpp.com there is advice to write doubles as:

double num {5.0}

Is there any real difference between that and:

double num {5}

It seems that my compiler (VS 2019) treats those as equivalent.

Solution

  • For that specific case, they are effectively equivalent, however, that's not always the case.

    For example:

    #include <iostream>

void foo(int v) {
  std::cout << "foo(int) called\n";
}

void foo(double v) {
  std::cout << "foo(double) called\n";
}

int main() {
  foo(5.0);
  foo(5);
}

    That program produces:

    foo(double) called
foo(int) called

    If only for this reason, it's good to get into the habit of always using a double literal when you want to express a double value, even if an int literal would have worked just as well. Otherwise, sooner or later, you will run into some surprises.