C# 判断字符串为Null或空的方法

判断字符串为Null或空的方法

1. IsNullOrEmpty
2. p == null || p == “”
3. p == null && p.Length == 0: 861ms
4. (p +”“).Length == 0: 1050ms

测试结果

测试1
- IsNullOrEmpty: 943ms
- p == null || p == “”: 1093ms
- p == null || p.Length == 0: 831ms
- (p +”“).Length == 0: 1115ms
测试2
- IsNullOrEmpty: 850ms
- p == null || p == “”: 1005ms
- p == null || p.Length == 0: 847ms
- (p +”“).Length == 0: 1077ms

结论

1. p == null || p.Length == 0 最快
2. IsNullOrEmpty与p == null || p.Length == 0 差距很小。
3.

Code

 var sw = new System.Diagnostics.Stopwatch();            var p = default(string);            var q = "";            var r = "str";            sw.Reset();            sw.Start();            for (var i = 1; i < 100000000; i++)            {                var pR = string.IsNullOrEmpty(p);                var qR = string.IsNullOrEmpty(q);                var rR = string.IsNullOrEmpty(r);            }            sw.Stop();            Console.WriteLine("IsNullOrEmpty: " + sw.ElapsedMilliseconds.ToString() + "ms");            sw.Reset();            sw.Start();            for (var total = 1; total < 100000000; total++)            {                var pR = p == null || p == "";                var qR = q == null || q == "";                var rR = r == null || r == "";            }            sw.Stop();            Console.WriteLine("p == null || p == \"\": " + sw.ElapsedMilliseconds.ToString() + "ms");            sw.Reset();            sw.Start();            for (var total = 1; total < 100000000; total++)            {                var pR = p == null || p.Length == 0;                var qR = q == null || q.Length == 0;                var rR = r == null || r.Length == 0;            }            sw.Stop();            Console.WriteLine("p == null || p.Length == 0: " + sw.ElapsedMilliseconds.ToString() + "ms");            sw.Reset();            sw.Start();            for (var total = 1; total < 100000000; total++)            {                var pR = (p +"").Length == 0;                var qR = (q +"").Length == 0;                var rR = (r +"").Length == 0;            }            sw.Stop();            Console.WriteLine("(p +\"\").Length == 0: " + sw.ElapsedMilliseconds.ToString() + "ms");