for循环与while循环效率对比·5年以下编程经验必看C#】

for效率测试代码：

using System;
using System.Diagnostics;
namespace Action
{
    class Program
    {
        static void Main(string[] args)
        {
            GC.Collect();//清理一下先
            Random ra = new Random();
            int count = 1000000;//100W
            DateTime start = DateTime.Now;
            for (int i = 0; i < count; i++)
            {
                new String(""+i);
            }
            DateTime end = DateTime.Now;
            double usedMemory = Process.GetCurrentProcess().WorkingSet64 / 1024.0 / 1024.0;
            Console.WriteLine("耗时：" + (end - start).TotalMilliseconds + "毫秒");
            Console.WriteLine("消耗内存:" + usedMemory + "M");
        }
    }
}

100W次消耗时间50.88ms，消耗内存19.50M

while效率测试代码：

using System;
using System.Diagnostics;
namespace Action
{
    class Program
    {
        static void Main(string[] args)
        {
            GC.Collect();//清理一下先
            Random ra = new Random();
            int count = 1000000;//100W
            DateTime start = DateTime.Now;
            int i = 0;
            while (i < count)
            {
                new String("" + i);
                i++;
            }
            DateTime end = DateTime.Now;
            double usedMemory = Process.GetCurrentProcess().WorkingSet64 / 1024.0 / 1024.0;
            Console.WriteLine("耗时：" + (end - start).TotalMilliseconds + "毫秒");
            Console.WriteLine("消耗内存:" + usedMemory + "M");
        }
    }
}

100W次消耗时间50.92ms，消耗内存19.59M

编码文件对比：

for:

while:

由于不能编入太多文字就只能截图了。

总结：

1、for循环与while循环效率测试上看差不多。

2、从编码上看，编译的exe文件完全相同，应该字节码是一样一样的。

3、在C#中两种循环效果相同。

单独方法编译测试：

public void forTest(){
        int i;
        for (i = 0;i<100000000;i++){
        }
    }
public void whileTest(){
        int i=0;
        while (i<100000000){
            i++;
        }
    }

但看两端代码编译后Code都一样：【i小于100000000】

Code:
      stack=5, locals=4, args_size=1
         0: invokestatic  #2                  // Method java/lang/System.currentTimeMillis:()J
         3: lstore_1
         4: iconst_0
         5: istore_3
         6: iload_3
         7: ldc           #3                  // int 100000000
         9: if_icmpge     18
        12: iinc          3, 1
        15: goto          6
        18: getstatic     #4                  // Field java/lang/System.out:Ljava/io/PrintStream;
        21: invokestatic  #2                  // Method java/lang/System.currentTimeMillis:()J
        24: lload_1
        25: lsub
        26: invokevirtual #5                  // Method java/io/PrintStream.println:(J)V
        29: return