C# 大小写转换

C#通过ToUpper()方法将字符串转换成大写，代码如下：

1 string sentence= "this is in upper case.";
2 Console.WriteLine(sentence.ToUpper()); 

C#通过ToLower()方法将字符串转换成小写，代码如下：

1 string sentence= "this is in Lower case.";
2 Console.WriteLine(sentence.ToLower());