Here are some simple syntactical comparisons between IDL and MATLAB. (Please note that I am not a real MATLAB user!) An obvious difference is that IDL does not need a ';' or other character to terminate a statement as the end of line is considered to be a terminator unless '&' is used to explicitly denote a continuation line. Both languages are array/matrix oriented but the array syntax in IDL is closer to Fortran.

    IDL                        MATLAB               comments

print,...,format='...'       fprintf(....)         NB: format statement is not 
                                                      compulsory in IDL

&		;				    multiple statements 

$	      no ;				    continuation        

;		!				    in-line comments    

*               :				    ranges in arrays