This is two-way condition in C – 'if-else' condition. If programmer wants to execute one set of statements on success case of one condition. How to replace multiple if statements i to more compact code/class in C#? Ask Question Asked 2 years, 8 months ago. Active 2 years, 6 months ago. Viewed 964 times 2. I'm having a problem converting multiple if statements (like in the example below) into more compact code. I though about tables or multidimensional arrays, but maybe you guys know.

Active2 years, 10 months ago

I've come across a situation where I have a bunch of 'systems' that need to be initialized in sequence, with the next system only being initialized if all of the proceeding systems initialized successfully.

This has led me to a whole slew of nested if - else statements. Here's some pseudo-code for visualization.

I find that this starts to look like a mess when you get even a handful of levels to it.

Now I thought of using a switch statement instead, starting at the first case and falling through to the other cases on success, only breaking if there's an error.

Now, I like this a lot better. I find it much easier to read, especially with some decent comments, but I'm fairly new to programming.

So, my question is: Seeing how this is not how switch statements are traditionally used(at least from what I've seen), is something like this acceptable, or would this be considered bad form?

Being new to programming, I'm trying not to develop too many bad habits that might frustrate and make things more difficult for other programmers down the road.

I did a search, but most of what I found had to do with replacing chains of if - else if statements, not replacing nested ones.

liquidhand

liquidhandliquidhand

4 Answers

Reference all of the systems in an array, for example an std::vector<mySystem*>, and loop over them sequentially, breaking off on the first fail. This way your entire code is reduced to less than 5 lines of code, even for 500+ systems.

The suggested switch hack is an evil example of XY problem solving: your real problem is that you don't have the array of systems, and are using named variables, thus eliminating all options to more flexibly use all systems, like in a loop.

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Niels KeurentjesNiels Keurentjes

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Assuming that all your system#Init() calls are known at compile time, you can very easily put them in a table and then iterate over that table.

However, your existing code looks incorrect since the first mainInit() only calls system1Init() and then exits. Probably not what you wanted in the first place.

Would the switch answer your problem? Not as it was written. That is, if you wanted to call the mainInit() function with a counter, it could be useful. Drupal uses that mechanism:

Note that the table mechanism works the same way as the switch. As long as all the code is found in the systemNInit() functions (and it should be), the switch does not add anything, so you could do something like this too:

Calling the mainInit() with an index can be helpful in case you want to 'de-initialize' properly:

Alexis WilkeAlexis Wilke

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Use custom exceptions with clear error messages and add a try-catch-report-die around the code in main(). Exceptions are there to specifically make your case look good by making 'bad path' implicit.

bobahbobah

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BetaBeta

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Not the answer you're looking for? Browse other questions tagged c++conditional-statementsnested-if or ask your own question.

The IF function allows you to make a logical comparison between a value and what you expect by testing for a condition and returning a result if True or False.

• =IF(Something is True, then do something, otherwise do something else)

So an IF statement can have two results. The first result is if your comparison is True, the second if your comparison is False.

IF statements are incredibly robust, and form the basis of many spreadsheet models, but they are also the root cause of many spreadsheet issues. Ideally, an IF statement should apply to minimal conditions, such as Male/Female, Yes/No/Maybe, to name a few, but sometimes you might need to evaluate more complex scenarios that require nesting* more than 3 IF functions together.

* “Nesting” refers to the practice of joining multiple functions together in one formula.

Technical details

Use the IF function, one of the logical functions, to return one value if a condition is true and another value if it's false.

Syntax

IF(logical_test, value_if_true, [value_if_false])

For example:

• =IF(A2>B2,'Over Budget','OK')
• =IF(A2=B2,B4-A4,')

Argument name	Description
logical_test (required)	The condition you want to test.
value_if_true (required)	The value that you want returned if the result of logical_test is TRUE.
value_if_false (optional)	The value that you want returned if the result of logical_test is FALSE.

Remarks

While Excel will allow you to nest up to 64 different IF functions, it’s not at all advisable to do so. Why?

• Multiple IF statements require a great deal of thought to build correctly and make sure that their logic can calculate correctly through each condition all the way to the end. If you don’t nest your formula 100% accurately, then it might work 75% of the time, but return unexpected results 25% of the time. Unfortunately, the odds of you catching the 25% are slim.
• Multiple IF statements can become incredibly difficult to maintain, especially when you come back some time later and try to figure out what you, or worse someone else, was trying to do.

If you find yourself with an IF statement that just seems to keep growing with no end in sight, it’s time to put down the mouse and rethink your strategy.

Let’s look at how to properly create a complex nested IF statement using multiple IFs, and when to recognize that it’s time to use another tool in your Excel arsenal.

Examples

Following is an example of a relatively standard nested IF statement to convert student test scores to their letter grade equivalent.