cm 3,711,863  Jan. 16, 1973
Primary Examiner—Raulfe B. Zache
Attorney—James A. Pershon et al.
A procedure for controlling a data processing system by a computer program that compares two versions of a source program and identifies the difference between the two. The program compares the two versions until a noncomparison is determined. The program then continues to compare each line in the base version to each line in the modified version until a comparison is found. The program then verifies that it is in the same area of both files by checking for an identical symbolic address and proceeds to check the statements preceding the identical symbolic addresses by working backwards until a noncompare is again detected. The test that defines the smallest area of noncomparison delineates the changes. The program then examines the statements in the noncomparing area to signify whether the noncomparison is due to an addition, deletion or modification.
11 Claims, 16 Drawing Figures
 SOURCE CODE COMPARATOR COMPUTER PROGRAM
 Inventor: Delwin W. Bloom, Phoenix, Ariz.
 Assignee: Honeywell Information Systems Inc., Waltham, Mass.
 Filed: Jan. 21, 1972
 Appl. No.: 219,721
 U.S. CI 444/1
 Int. CI G06f9/16
 Field of Search 444/1; 235/153 AK
 References Cited
UNITED STATES PATENTS
3,544,777 12/1970 Winkler 235/153 AK
3,568,156 3/1971 Thompson 444/1