Change string into first letter Uppercase, the rest of the string to lower case

Hey, I've figured out how to change the first letter of a string into a capital letter, but how would I go around to keep the rest of the string lower case? For example:

"dEFiNiTiOn" --> "Definition"

I used this to change the first letter to upper case:

Code (CSharp):

1. if(str.Length == 0){
2.             return;
3.         }else if(str.Length == 1){
4.             char.ToUpper(str[0]);
5.         }else{
6.             str = char.ToUpper(str[0]) + str.Substring(1);
7.         }

}

 

Here are two implementations, one is thread safe but will allocate more memory, the other is not thread safe but only allocates the new string by reusing the string builder:

Code (CSharp):

1. using System.Text;
2.                    
3. public static class StringExt
4. {
5.     // thread safe
6.     public static string ToPascalCase_Safe(this string aText)
7.     {
8.         if (aText == null || aText.Length < 1)
9.             return aText;
10.         StringBuilder sb = new StringBuilder(aText);
11.         sb[0] = char.ToUpper(sb[0]);
12.         for(int i = 1; i < sb.Length; i++)
13.             sb[i] = char.ToLower(sb[i]);
14.         return sb.ToString();
15.     }
16.    
17.     // not thread safe, but reduces garbage
18.     private static StringBuilder m_SB = new StringBuilder();
19.     public static string ToPascalCase(this string aText)
20.     {
21.         if (aText == null || aText.Length < 1)
22.             return aText;
23.         m_SB.Clear();
24.         m_SB.Append(char.ToUpper(aText[0]));
25.         for(int i = 1; i < aText.Length; i++)
26.             m_SB.Append(char.ToLower(aText[i]));
27.         return m_SB.ToString();
28.     }
29. }
30.  

Both are extension methods. So you can simply do

Code (CSharp):

1. str = str.ToPascalCase();

To replace the original string with the converted string.

 

Super simple, feel stupid for not thinking of that, thank you

 

To be even more gently to the memory I suggest to initalize the static StringBuilder instance to a reasonable size.

Code (CSharp):

1.   private static StringBuilder m_SB = new StringBuilder(64);

Here are more solutions to the given problem:
https://stackoverflow.com/questions...-a-string-upper-case-with-maximum-performance

A nice one is this

Code (CSharp):

1. return char.ToUpper(str[0]) + str.Substring(1)