What was Hollerith data?
Stunningly, Fortran-66 had no character data type – only numeric types. In order to deal with characters, typeless constants, called Hollerith constants, were used. An example of a Hollerith constant is 3HABC – which specifies a 3 character constant with the value ‘ABC’ in it. Since a Hollerith constant was typeless, it could be placed into any numeric data type without type conversion. Per the ’66 Standard, Hollerith constants could only be used in 3 places: • In DATA statements • As actual arguments in a CALL statement – e.g., CALL SUB (3HABC) • In FORMAT statements Virtually all compilers extended the above to allow Hollerith constants to be used in expressions. Of interest, consider the case where a data type could hold more than the number of characters specified in the Hollerith constant. In this case, the compiler was required to left-justify the characters and ‘blank fill’ the unused bits. Note that ‘zero-fill’ variants, with both right- and left-justification, were common exte
