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!
转载于:https://www.cnblogs.com/LoveLyre/archive/2011/09/02/2163535.html