猜猜几种c#字符串连接所消耗时间的先后?

猜猜几种c#字符串连接所消耗时间的先后?

1. 字符串字面值直接连加

test = "I1" + "I2" + "I3" + "I4" + "I5";

2.字符串字面值用+=相加

    test = "I6";
    test += "I7";
    test += "I8";
    test += "I9";
    test += "I10";

3.sn为字符串变量

 test = s1 + s2 + s3 + s4 + s5;

4.

   test = s1;
   test += s2;
   test += s3;
   test += s4;
   test += s5; 

 

5.csn为字符串常量

 test = cs1 + cs2 + cs3 + cs4 + cs5;

6.

    test = cs1;
    test += cs2;
    test += cs3;
    test += cs4;
    test += cs5;

以上6种方式各循环10000000次,你能猜出他们执行所需时间的的顺序吗? 如果你是c++程序员,我觉得对于这个问题你可能会不占优势,你可能想到临时变量之类的吧.

看测试代码:

            const int Num = 10000000;
            int end;
            string test = "";

            int start = Environment.TickCount;
            for (int i = 0; i < Num; i++)
            {
                test = "I1" + "I2" + "I3" + "I4" + "I5";
            }
            end = Environment.TickCount;
            Console.WriteLine("字符串字面值:" + (end - start));

            start = Environment.TickCount;
            for (int i = 0; i < Num; i++)
            {
                test = "I6";
                test += "I7";
                test += "I8";
                test += "I9";
                test += "I10";
            }
            end = Environment.TickCount;
            Console.WriteLine("字符串字面值:" + (end - start));


            string s1 = "e1";
            string s2 = "e2";
            string s3 = "e3";
            string s4 = "e4";
            string s5 = "e5";

            start = Environment.TickCount;
            for (int i = 0; i < Num; i++)
            {
                test = s1 + s2 + s3 + s4 + s5;
            }
            end = Environment.TickCount;
            Console.WriteLine("变量:" + (end - start));

            s1 = "h1";
            s2 = "h2";
            s3 = "h3";
            s4 = "h4";
            s5 = "h5";
            start = Environment.TickCount;
            for (int i = 0; i < Num; i++)
            {
                test = s1;
                test += s2;
                test += s3;
                test += s4;
                test += s5;
            }
            end = Environment.TickCount;
            Console.WriteLine("变量:" + (end - start));


            const string cs1 = "H1";
            const string cs2 = "H2";
            const string cs3 = "H3";
            const string cs4 = "H4";
            const string cs5 = "H5";

            start = Environment.TickCount;
            for (int i = 0; i < Num; i++)
            {
                test = cs1 + cs2 + cs3 + cs4 + cs5;
            }
            end = Environment.TickCount;
            Console.WriteLine("字符串常量 :" + (end - start));

            start = Environment.TickCount;
            for (int i = 0; i < Num; i++)
            {
                test = cs1;
                test += cs2;
                test += cs3;
                test += cs4;
                test += cs5;
            }
            end = Environment.TickCount;
            Console.WriteLine("字符串常量:" + (end - start));

        
   

你答对了吗?

上答案啦!