Add strtoupper() and strtolower() and improve description of substring()

diff --git a/Introduction-to-QuakeC.md b/Introduction-to-QuakeC.md
index 0cd22f18785a067e9ec5daf8d1cc9b228451fe44..aaa5fe20cc0df577a13e510f7da0a95112666199 100644 (file)
--- a/Introduction-to-QuakeC.md
+++ b/Introduction-to-QuakeC.md
@@ -150,14 +150,19 @@ A *string* in QuakeC is an immutable reference to a null-terminated character st
     strstrofs("haystack", "ac", 0) == 5;
     ```
 
+The offset defines from which starting position to search, and the return value is `–1` if no match is found. The offset returned is *0*-based, and to search in the whole string, a start offset of *0* would be used.
+
 -   **strreplace(old, new, string)** searches for certain characters in a string and replaces them with other characters, as in:
     ```c
     strreplace("de", "con", "destruction") == "construction";
     ```
 
-The offset defines from which starting position to search, and the return value is `–1` if no match is found. The offset returned is *0*-based, and to search in the whole string, a start offset of *0* would be used.
+-   **substring(string, startpos, length)** returns part of a string.
+
+The offset is *0*-based here, too. A length of `-1` designates the end of the string (it will return the part of the string after the start position), a length of `-2` designates the penultimate character of the string, and so on.
 
--   **substring(string, startpos, length)** returns part of a string. The offset is *0*-based here, too.
+-   **strtoupper(string)** capitalizes a string.
+-   **strtolower(string)** lowercases a string.
 
 Note that there are different kinds of *strings*, regarding memory management: