C# 字符串大小写转换

C#通过ToUpper()方法将字符串转换成大写串转

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

C#通过ToLower()方法将字符串转换成小写

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