Asp.ent (C #) 3 ways to judge an empty string and performance analysis _ Practical Tips

The 3 ways are:
String A= "";
1.if (a== "")
2.if (A==string.empty)
3.if (a.length==0)

3 methods are equivalent, so which one is the highest performance? I use the experiment to explain the problem.

Create 3 aspx pages (why use Web pages, mainly with Microsoft application Center Test)

WebForm1.aspx

Copy Code code as follows:

private void Page_Load (object sender, System.EventArgs e)
{
String A= "";
for (int i=0;i<=1000000;i++)
{
if (a== "")
{
}
}
}

Webform2.aspx

Copy Code code as follows:

private void Page_Load (object sender, System.EventArgs e)
{
String A= "";
for (int i=0;i<=1000000;i++)
{
if (a==string.empty)
{

}
}
}

Webform3.aspx

Copy Code code as follows:

private void Page_Load (object sender, System.EventArgs e)
{
String A= "";
for (int i=0;i<=1000000;i++)
{
if (a.length==0)
{
}
}
}

Set up 3 stress test projects under Microsoft Application Center test:

Test results:
WebForm1.aspx----------if (a== "")

webform2.aspx-------if (a==string.empty)

webform3.aspx-------if (a.length==0)

So 3 ways to quantify the result is 98,105,168:

Method	Results
if (a== "")	98
if (a==string.empty)	105
if (a.length==0)	168

So why is if (a.length==0) the fastest?
Because integer judgments are equal to the fastest, there is no complicated process, such as instantiation.

So: We recommend that you determine whether the string is empty if (a.length==0).