Patent US 6,236,993

A computer-implemented method and computer program product for comparing two data files to find matching data. The comparisons can be between dates, monetary units, or any other quantities. Comparisons are handled between files which differ by any predetermined function such as additive or multiplicative without using file wide delimiters, field boundary or field format information. An example of such a comparison are the additive differences resulting from aging files in a Year 2000 compliance testing method. The method can thus be used to test whether an effort to remediate a Year 2000 problem in a computer program was successful. Another example of such comparisons are the differences resulting from conversion between the monetary units of two countries or regions. The method can thus also be used to verify currency conversions. Data items are read from a first file and a second file and sequentially compared and, if a mismatch exists, it is determined whether the mismatch could be attributable to a difference in format, quantity, or both. An expected difference between two files may be input by a user of the program or may be automatically computed during operation.