1. A method for reducing false positives in a computer-based impact variables analysis and field expansion process conducted on at least one source code, the method comprising processor implemented steps of: a) receiving said at least one source code in at least one source language; b) parsing said received source code to generate at least one attribute and relation file; c) loading said generated at least one attribute and relation file in a repository database; d) identifying a first set of seed variables on which impact analysis is performed; e) performing an impact analysis on the first set of seed variables from the said repository; f) verifying said performed impact analysis to identify a second set of seed variables from the first set of seed variables that are not impacted; g) excluding the said identified second set of seed variables from the field expansion; and h) converting the at least one source code by expanding size of a third set of variables from the first set of variables in the at least one source code that are impacted.