Question

I have a class called AppSettings where I have an Array with a range of note frequencies. I’m getting several errors with the code below and I’m not sure what the problem is.

The error messages are:

• static data member of type 'const float [36] must be initialized out of line
• A brace enclosed initializer is not allowed here before '{' token
• Invalid in-class initialization of static data member of non-integral type

And the code:

class AppSettings{

public:
    static const float noteFrequency[36] = {
    //  C       C#      D       D#      E       F       F#      G       G#      A       A#      B
        130.81, 138.59, 146.83, 155.56, 164.81, 174.61, 185.00, 196.00, 207.65, 220.00, 223.08, 246.94,
        261.63, 277.18, 293.66, 311.13, 329.63, 349.23, 369.99, 392.00, 415.30, 440.00, 466.16, 493.88,
        523.25, 554.37, 587.33, 622.25, 659.25, 698.46, 739.99, 783.99, 830.61, 880.00, 932.33, 987.77
    };

};

As the name suggests this is just a header file with some settings and values I need throughout the app.

Answer 1

You can’t define the value of static class members within the class. You need to have a line like this in the class:

class AppSettings
{
public:
    static const float noteFrequency[];

And then in an implementation file for the class (AppSettings.cpp perhaps):

const float AppSettings::noteFrequency[] = { /* ... */ };

Also, you don’t need to specify the number within the [] here, because C++ is smart enough to count the number of elements in your initialization value.