c# ean 13 check Gen eral issues involved in 5 changing code are discussed 6 in depth in 24, 7 Refactoring. in Visual C#

Generate EAN-13 Supplement 5 in Visual C# Gen eral issues involved in 5 changing code are discussed 6 in depth in 24, 7 Refactoring.

Gen eral issues involved in 5 changing code are discussed 6 in depth in 24, 7 Refactoring.
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4 CROSS-REFERENCE
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Save the original source code Before you begin fixing the defect, be sure to archive a version of the code that you can return to later. It s easy to forget which change in a group of changes is the significant one. If you have the original source code, at least you can compare the old and the new files and see where the changes are. Fix the problem, not the symptom You should fix the symptom too, but the focus should be on fixing the underlying problem rather than wrapping it in programming duct tape. If you
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de Complete
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23. Debugging
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don t thoroughly understand the problem, you re not fixing the code. You re fixing the symptom and making the code worse. Suppose you have this code:
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Java Example of Code That Needs to Be Fixed
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for ( claimNumber = 0; claimNumber < numClaims[ client ]; claimNumber++ ) { sum[ client ] = sum[ client ] + claimAmount[ claimNumber ]; }
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Further suppose that when client equals 45, sum turns out to be wrong by $3.45. Here s the wrong way to fix the problem:
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CODING HORROR
Java Example of Making the Code Worse by Fixing It
for ( claimNumber = 0; claimNumber < numClaims[ client ]; claimNumber++ ) { sum[ client ] = sum[ client ] + claimAmount[ claimNumber ]; } if ( client == 45 ) { sum[ 45 ] = sum[ 45 ] + 3.45; }
4 Here s the fix.
Now suppose that when client equals 37 and the number of claims for the client is 0, you re not getting 0. Here s the wrong way to fix the problem:
CODING HORROR
Java Example of Making the Code Worse by Fixing It (continued)
for ( claimNumber = 0; claimNumber < numClaims[ client ]; claimNumber++ ) { sum[ client ] = sum[ client ] + claimAmount[ claimNumber ]; } if ( client == 45 ) { sum[ 45 ] = sum[ 45 ] + 3.45; } else if ( ( client == 37 ) && ( numClaims[ client ] == 0 ) ) { sum[ 37 ] = 0.0; }
7 Here s the second fix.
If this doesn t send a cold chill down your spine, you won t be affected by anything else in this book either. It s impossible to list all the problems with this approach in a book that s only a little over 900 pages long, but here are the top three: The fixes won t work most of the time. The problems look as though they re the result of initialization defects. Initialization defects are, by definition, unpredictable, so the fact that the sum for client 45 is off by $3.45 today doesn t tell you anything about tomorrow. It could be off by $10,000.02, or it could be correct. That s the nature of initialization defects.
de Complete
23. Debugging
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It s unmaintainable. When code is special-cased to work around errors, the special cases become the code s most prominent feature. The $3.45 won t always be $3.45, and another error will show up later. The code will be modified again to handle the new special case, and the special case for $3.45 won t be removed. The code will become increasingly barnacled with special cases. Eventually the barnacles will be too heavy for the code to support, and the code will sink to the bottom of the ocean a fitting place for it. It uses the computer for something that s better done by hand. Computers are good at predictable, systematic calculations, but humans are better at fudging data creatively. You d be wiser to treat the output with Whiteout and a typewriter than to monkey with the code.
Change the code only for good reason Related to fixing symptoms is the technique of changing code at random until it seems to work. The typical line of reasoning goes like this: This loop seems to contain a defect. It s probably an off-by-one error, so I ll just put a -1 here and try it. OK. That didn t work, so I ll just put a +1 in instead. OK. That seems to work. I ll say it s fixed.
As popular as this practice is, it isn t effective. Making changes to code randomly is like poking a Pontiac Aztek with a stick to see if it moves. You re not learning anything; you re just goofing around. By changing the program randomly, you say in effect, I don t know what s happening here, but I ll try this change and hope it works. Don t change code randomly. That s voodoo programming. The more different you make it without understanding it, the less confidence you ll have that it works correctly. Before you make a change, be confident that it will work. Being wrong about a change should leave you astonished. It should cause self-doubt, personal reevaluation, and deep soul-searching. It should happen rarely.
Make one change at a time Changes are tricky enough when they re done one at a time. When done two at a time, they can introduce subtle errors that look like the original errors. Then you re in the awkward position of not knowing whether (1) you didn t correct the error, (2) you corrected the error but introduced a new one that looks similar, or (3) you didn t correct the error and you introduced a similar new error. Keep it simple: Make just one change at a time.
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