STRING-UPCASE

in a given string, turn lower-case characters into upper-case 
Major Section:  PROGRAMMING

For a string x, (string-upcase x) is the result of applying char-upcase to each character in x.

The guard for string-upcase requires its argument to be a string containing only standard characters.

String-upcase is a Common Lisp function. See any Common Lisp documentation for more information.