C#•3w ago

✅ Static keyword

C#
static readonly City[] cities = [
    new City("Tokyo", 37_833_000),
    new City("Delhi", 30_290_000),
    new City("Shanghai", 27_110_000),
    new City("São Paulo", 22_043_000),
    new City("Mumbai", 20_412_000),
    new City("Beijing", 20_384_000),
    new City("Cairo", 18_772_000),
    new City("Dhaka", 17_598_000),
    new City("Osaka", 19_281_000),
    new City("New York-Newark", 18_604_000),
    new City("Karachi", 16_094_000),
    new City("Chongqing", 15_872_000),
    new City("Istanbul", 15_029_000),
    new City("Buenos Aires", 15_024_000),
    new City("Kolkata", 14_850_000),
    new City("Lagos", 14_368_000),
    new City("Kinshasa", 14_342_000),
    new City("Manila", 13_923_000),
    new City("Rio de Janeiro", 13_374_000),
    new City("Tianjin", 13_215_000)
];

static readonly Country[] countries = [
    new Country ("Vatican City", 0.44, 526, [new City("Vatican City", 826)]),
    new Country ("Monaco", 2.02, 38_000, [new City("Monte Carlo", 38_000)]),
    new Country ("Nauru", 21, 10_900, [new City("Yaren", 1_100)]),
    new Country ("Tuvalu", 26, 11_600, [new City("Funafuti", 6_200)]),
    new Country ("San Marino", 61, 33_900, [new City("San Marino", 4_500)]),
    new Country ("Liechtenstein", 160, 38_000, [new City("Vaduz", 5_200)]),
    new Country ("Marshall Islands", 181, 58_000, [new City("Majuro", 28_000)]),
    new Country ("Saint Kitts & Nevis", 261, 53_000, [new City("Basseterre", 13_000)])
];

C#
static readonly City[] cities = [
    new City("Tokyo", 37_833_000),
    new City("Delhi", 30_290_000),
    new City("Shanghai", 27_110_000),
    new City("São Paulo", 22_043_000),
    new City("Mumbai", 20_412_000),
    new City("Beijing", 20_384_000),
    new City("Cairo", 18_772_000),
    new City("Dhaka", 17_598_000),
    new City("Osaka", 19_281_000),
    new City("New York-Newark", 18_604_000),
    new City("Karachi", 16_094_000),
    new City("Chongqing", 15_872_000),
    new City("Istanbul", 15_029_000),
    new City("Buenos Aires", 15_024_000),
    new City("Kolkata", 14_850_000),
    new City("Lagos", 14_368_000),
    new City("Kinshasa", 14_342_000),
    new City("Manila", 13_923_000),
    new City("Rio de Janeiro", 13_374_000),
    new City("Tianjin", 13_215_000)
];

static readonly Country[] countries = [
    new Country ("Vatican City", 0.44, 526, [new City("Vatican City", 826)]),
    new Country ("Monaco", 2.02, 38_000, [new City("Monte Carlo", 38_000)]),
    new Country ("Nauru", 21, 10_900, [new City("Yaren", 1_100)]),
    new Country ("Tuvalu", 26, 11_600, [new City("Funafuti", 6_200)]),
    new Country ("San Marino", 61, 33_900, [new City("San Marino", 4_500)]),
    new Country ("Liechtenstein", 160, 38_000, [new City("Vaduz", 5_200)]),
    new Country ("Marshall Islands", 181, 58_000, [new City("Majuro", 28_000)]),
    new Country ("Saint Kitts & Nevis", 261, 53_000, [new City("Basseterre", 13_000)])
];

Hello guys, I have a small question. Here, notice we use the static keyword with the array Country and City. My question is, static keyword can only be used in the class where Country and City exist? That is, say we have class City and Country, in both classes we would have the declaration of an array of their respective type with static and readonly keyword? We can't use static keyword for a variable in our Program.cs for example?

6 Replies

FusedQyou•3w ago

I'm not entirely sure what you are asking The static keyword basically means "single instance"

Angius•3w ago

You can store this data this way, sure. I'd say it would be better to store it in a file or database though

FusedQyou•3w ago

It is not related to your class in any way

Angius•3w ago

You can use static in the Program class. If you use top-level statements then no, since that behaves like a method body Local variables cannot be static

FusedQyou•3w ago

If you make it static in this case, your array will not be created with each instance of the containing class you create. It would be better for performance, but that also assumes the array is not mutated in any way. Otherwise you risk concurrency or undefined behaviour

FakerOP•3w ago

oh ok I see, didn't know why I got confused with the static keyword but it's clearer now, thanks !

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✅ Static keyword

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