Split a character string based on change of character: Difference between revisions
Split a character string based on change of character (view source)
Revision as of 03:19, 7 February 2017
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An alternative method would be to prepare the entire output in a CHARACTER variable then write that, but this means answering the maddening question "how long is a piece of string?" for that variable, though later Fortran has arrangements whereby a text variable is resized to suit on every assignment, as in <code>TEMP = TEMP // more</code> - but this means repeatedly copying the text to the new manifestation of the variable. Still another approach would be to prepare an array of fingers to each split point so that the final output would be a single WRITE using that array, and again, how big must the array be? At most, as big as the number of characters in TEXT. With F90, subroutines can declare arrays of a size determined on entry, with something like <code>INTEGER A(LEN(TEXT))</code>
If the problem were to be solved by writing a "main line" only, there would have to be a declaration of the text variable there but since a subroutine can receive a CHARACTER variable of any size (the actual size is passed as a secret parameter),
For this example a DO-loop stepping along the text is convenient, but in a larger context it would probably be most useful to work along the text with fingers L1 and L2 marking the start and finish positions of each sequence. <lang Fortran> SUBROUTINE SPLATTER(TEXT) !Print a comma-separated list. Repeated characters constitute one item.
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