(macOS) make a list of Japanese GENGO/日本の元号のリスト作る。

listEraSymbols.m

// Compile:
//      cc -framework Foundation listEraSymbols.m -o listEraSymbols

// Usage: listEraSymbols [locale]
// Examples:
//      listEraSymbols          -- Gengo List in default Language (C locale)
//      listEraSymbols ja_JP    -- Gengo List in Japanese
//      listEraSymbols zh_CN    -- Gengo List in Chinese
//      listEraSymbols en_US    -- Gengo List in English

#import <Foundation/Foundation.h>

int main(int argc, char *argv[])
{
    NSString *loc = @"C";
    NSCalendar *jcal = [NSCalendar calendarWithIdentifier: NSCalendarIdentifierJapanese];

    if (argc > 1)
        loc = [NSString stringWithUTF8String: argv[1]];

    jcal.locale = [NSLocale localeWithLocaleIdentifier: loc];
    for(NSString * era in jcal.longEraSymbols){
        NSLog(@"%@", era);
    }
}