C++ Tutorial/Data Types/enum — различия между версиями
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Текущая версия на 13:31, 25 мая 2010
Содержание
A Demonstration of Enumerated Constants
<source lang="cpp">#include <iostream> int main() {
enum Days { Sunday, Monday, Tuesday,Wednesday, Thursday, Friday, Saturday }; Days today; today = Monday; if (today == Sunday || today == Saturday) std::cout << " love the weekends!\n"; else std::cout << "\nBack to work.\n"; return 0;
}</source>
An enumeration static_cast
<source lang="cpp">#include <iostream> using std::cout; enum Language { English, French, German, Italian, Spanish }; int main() {
Language tongue = German; tongue = static_cast<Language>(tongue + 1); cout << "\n Current language is now " << tongue << std::endl;
return 0;
}</source>
Current language is now 3
An enumeration variable
<source lang="cpp">#include <iostream> using std::cout; enum Language { English, French, German, Italian, Spanish }; int main() {
Language tongue = German; cout << "\n Current language is " << tongue; return 0;
}</source>
Current language is 2
Compare enum elements
<source lang="cpp">#include<iostream.h> enum color{
RED=1, GREEN=6, BLUE=9
}; int main() {
enum color v1=RED,v2; cout<<"RED="<<RED<<endl; cout<<"GREEN="<<GREEN<<endl; cout<<"BLUE="<<BLUE<<endl; cout<<"v1="<<v1<<endl; v2=GREEN; cout<<"(v1<v2)="<<(v1<v2)<<endl;
}</source>
RED=1 GREEN=6 BLUE=9 v1=1 (v1<v2)=1
Define and output an enumeration
<source lang="cpp">#include <iostream> using std::cout; enum Language { English, French, German, Italian, Spanish }; int main() {
cout << "\nPossible languages are:\n" << English << ". English\n" << French << ". French\n" << German << ". German\n" << Italian << ". Italian\n" << Spanish << ". Spanish\n"; return 0;
}</source>
Possible languages are: 0. English 1. French 2. German 3. Italian 4. Spanish
Demonstrate an enumeration.
<source lang="cpp">#include <iostream> using namespace std;
enum Letter { A, B, C, D, E };
char name[][20] = {
"Automobile", "Bank", "Cat", "Day", "eagle"
};
int main() {
Letter how; how = A; cout << name[how] << "\n"; how = C; cout << name[how] << "\n"; how = D; cout << name[how] << "\n"; return 0;
}</source>
Automobile Cat Day
Return enum from a function
<source lang="cpp">#include <iostream>
enum ERR_CODE { SUCCESS, ERROR }; ERR_CODE f(int, int&, int&); int main() { int number = 2, squared, cubed; ERR_CODE result; result = f(number, squared, cubed); if (result == SUCCESS) { ; } else std::cout << "Error encountered!!\n"; return 0; } ERR_CODE f(int n, int &rSquared, int &rCubed) { return ERROR; // simple error code }</source>
Error encountered!!
Using consts and enums in Arrays
<source lang="cpp">#include <iostream> using namespace std; int main() {
enum WeekDays { Sun, Mon, Tue,Wed, Thu, Fri, Sat, DaysInWeek }; int ArrayWeek[DaysInWeek] = { 10, 20, 30, 40, 50, 60, 70 }; cout << "The value at Tuesday is: " << ArrayWeek[Tue]; return 0;
}</source>