C# for循环

for循环重复执行代码块，直到指定的条件表达式求值为false。

for循环剖析：

for (initialization; condition; iterator)
{
  body
}

• 初始化 - 初始化语句设置初始条件，并在进入循环体之前仅运行一次。
• condition - 布尔表达式，用于确定循环体是应该再次执行还是循环应该退出。
• iterator - 在循环体的每次迭代后执行。

例1

for (int i = 0; i < 5; i++)
 {
    Console.WriteLine("Number " + i);
 }

输出

> Number 0
> Number 1
> Number 2
> Number 3
> Number 4

例2

int j = 0;
for (int i = 0; j < 5; i++)
{
  Console.WriteLine("Numbers {0} {1}", i, j);
  j++;
}

输出

> Numbers 0 0
> Numbers 1 1
> Numbers 2 2
> Numbers 3 3
> Numbers 4 4

实施例3-实施例2的简化

for (int i = 0, j = 0; i < 5 && j < 5; i++, j++)
{
  Console.WriteLine("Numbers {0} {1}", i, j);
}

输出

> Numbers 0 0
> Numbers 1 1
> Numbers 2 2
> Numbers 3 3
> Numbers 4 4

例4

for (int i = 5; i > 0; i--)
{
  Console.WriteLine("Number " + i);
}

输出

> Number 5
> Number 4
> Number 3
> Number 2
> Number 1

例5

// Infinite loop - The loop body is executed infinitely
for (; ;)
{
  Console.WriteLine("The universe is infinite");
}

// Anything after infinite loop is reported as "Unreachable code detected" in Visual Studio
Console.WriteLine("Never considered for execution");

输出

> The universe is infinite
> The universe is infinite
> The universe is infinite
> ....
> ....

例6

int i = 0;
for (; i < 5;)
{
  Console.WriteLine("Number " + i);
  i++;
}

输出：

> Number 0
> Number 1
> Number 2
> Number 3
> Number 4

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