今天在寫代碼時突然想起測試經常用Microsoft.VisualBasic.Information.IsNumeric判斷 url參數是否為數字時的這個方法的效率
因為數字是字串是直接使用的,所以不需要轉型,也就沒有用tryparse
結果一測試嚇一跳,這個方法的效率是如此的低,再測試了下tryparse還不錯,正則的也比較差,
沒什麼技術含量,看結果吧:
先拓展下字串:
code
public static class Common
{
//isDigit
public static bool isNumberic1(this string _string)
{
if (string.IsNullOrEmpty(_string))
return false;
foreach (char c in _string)
{
if (!char.IsDigit(c))//if(c<'0' || c>'9')//最好的方法,在下面測試資料中再加一個0,然後這種方法效率會搞10毫秒左右
return false;
}
return true;
}
//vb isnumberic
public static bool isNumberic2(this string _string)
{
return !string.IsNullOrEmpty(_string) && Microsoft.VisualBasic.Information.IsNumeric(_string);
}
//try parse
public static bool isNumberic3(this string _string)
{
if (string.IsNullOrEmpty(_string))
return false;
int i = 0;
return int.TryParse(_string, out i);
}
//try catch
public static bool isNumberic4(this string _string)
{
if (string.IsNullOrEmpty(_string))
return false;
try { int.Parse(_string); }
catch { return false; }
return true;
}
//regex
public static bool isNumberic5(this string _string)
{
return !string.IsNullOrEmpty(_string) && Regex.IsMatch(_string, "^\\d+$");
}
}
測試的代碼:
code
class Program
{
static void Main(string[] args)
{
Test("1234");
Test("1234a");
Test("a1234");
Test("");
Test(null);
}
static void Test(string str)
{
bool res1 = false, res2 = false, res3 = false, res4 = false, res5 = false;
Stopwatch wat = new Stopwatch();
wat.Start();//
for (int i = 1; i < 100000; i++)
{
res1 = str.isNumberic1();
}
wat.Stop();
Console.WriteLine("isDigit {0}:{1},{2}", str, wat.ElapsedMilliseconds, res1);
wat.Reset();
wat.Start();
for (int i = 1; i < 100000; i++)
{
res2= str.isNumberic2();
}
wat.Stop();
Console.WriteLine("isNumberic {0}:{1},{2}", str, wat.ElapsedMilliseconds, res2);
wat.Reset();
wat.Start();
for (int i = 1; i < 100000; i++)
{
res3 = str.isNumberic3();
}
wat.Stop();
Console.WriteLine("try parse {0}:{1},{2}", str, wat.ElapsedMilliseconds, res3);
wat.Reset();
wat.Start();
for (int i = 1; i < 100000; i++)
{
res4 = str.isNumberic4();
}
wat.Stop();
Console.WriteLine("try catch {0}:{1},{2}", str, wat.ElapsedMilliseconds, res4);
wat.Reset();
wat.Start();
for (int i = 1; i < 100000; i++)
{
res5 = str.isNumberic5();
}
wat.Stop();
Console.WriteLine("regex {0}:{1},{2}", str, wat.ElapsedMilliseconds, res5);
Console.WriteLine();
}
}
下面是我原生測試結果
isDigit 1234:5,True
isNumberic 1234:166,True
try parse 1234:21,True
try catch 1234:22,True
regex 1234:134,True
isDigit 1234a:5,False
isNumberic 1234a:196,False
try parse 1234a:19,False
try catch 1234a:5182,False
regex 1234a:150,False
isDigit a1234:2,False
isNumberic a1234:184,False
try parse a1234:16,False
try catch a1234:5084,False
regex a1234:106,False
isDigit :1,False
isNumberic :0,False
try parse :0,False
try catch :1,False
regex :0,False
isDigit :1,False
isNumberic :0,False
try parse :1,False
try catch :1,False
regex :0,False
結果:迴圈判斷是否是數字字元效率是最高的
而VisualBasic的方法效率比較低了
順便測試了下VisualBasic裡的left和right方法效率也一樣的低,還不及substring的十分之一
所以VisualBasic裡雖然有幾個方法從名字看來比較好用,實際卻比較杯具。