实现IEnumerable接口的类可以进行简单迭代,例如foreach语句
using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;
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namespace IEnumerable接口
{
class Program
{
static void Main(string[] args)
{
A a = new A();
foreach (int? var in a)//当int值可能被赋空值时用?
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{
Console.WriteLine(var);
}
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}
}
class A : IEnumerable
{
int x = 1;
int y = 2;
int z = 3;
public IEnumerator GetEnumerator()
{
// int i = -1;
for (int i = 0; i <=3; i++)
{
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if (i == x)
{
yield return 1;
}
else if (i == y)
{
yield return 2;
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}
else if (i == z)
{
yield return 3;
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}
else
{
yield return null;
}
}
}
}
}
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