Validating Halstead´s theory for Pascal programs

M.H. Halstead´s theory (1977) has been validated for different languages, but Pascal programs seem to fit only partially with the theory. D.B. Johnston and A.M. Lister (1981) first recognized the lack of operators due to the structure of this language and proposed a modification of Halstead´s formula. The article confirms their results but suggests a correction to their formula, which is particularly necessary for large programs. Experimental results, obtained by examining about 550 Pascal programs, represent the widest test to date of Halstead theory with regard to Pascal programs