这是DOS系统的源代码

				SUMMARY lower upper MakeStr
				
				#include 
				
				char *lower(pstr)
				char *pstr;
				
				char *upper(pstr)
				char *pstr;
				
				DESCRIPTION
				
				lower and upper convert the string to lower and upper case.
				
				RETURN VALUE
				
				Return a pointer to converted string.
				
				IMPLEMENTATION
				
				Calls strlwr and strupr from C library.
				
				SEE ALSO
				
				
				NOTE
				
				
				EXAMPLE
				
				#include 
				
				char str[] = "Mixed Case String";
				
				main(c, argv)
				int c;
				char *argv[];
				{
				    char *pstrLower = lower(MakeStr(str));
				    char *pstrUpper = upper(MakeStr(str));
				
				    printf("%s\n%s\n%s\n", str, pstrLower, pstrUpper);
				}