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Questions tagged [conditional-statements]

"In computer science, conditional statements, conditional expressions and conditional constructs are features of a programming language which perform different computations or actions depending on whether a programmer-specified boolean condition evaluates to true or false. Apart from the case of branch prediction, this is always achieved by selectively altering the control flow based on some condition." -- Wikipedia

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Why do empty JavaScript arrays evaluate to true in conditional structures?

I was encountering a lot of bugs in my code because I expected this expression: Boolean([]); to evaluate to false. But this wasn't the case as it evaluated to true. Therefore, functions that possibly returned [] like this: // Where myCollection…
racl101
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Can you use if/else conditions in CSS?

I would like to use conditions in my CSS. The idea is that I have a variable that I replace when the site is run to generate the right style-sheet. I want it so that according to this variable the style-sheet changes! It looks like: [if {var} eq 2…
Haim Evgi
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An expensive jump with GCC 5.4.0

I had a function which looked like this (showing only the important part): double CompareShifted(const std::vector& l, const std::vector &curr, int shift, int shiftY) { ... for(std::size_t i=std::max(0,-shift);i
Jakub Jůza
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Creating a new column based on if-elif-else condition

I have a DataFrame df: A B a 2 2 b 3 1 c 1 3 I want to create a new column based on the following criteria: if row A == B: 0 if rowA > B: 1 if row A < B: -1 so given the above table, it should be: A B C a 2 2 …
nutship
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Is it good practice to use the xor operator for boolean checks?

I personally like the exclusive or, ^, operator when it makes sense in the context of boolean checks because of its conciseness. I much prefer to write if (boolean1 ^ boolean2) { //do it } than if((boolean1 && !boolean2) || (boolean2 &&…
Peter
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If condition A is matched, condition B needs to be matched in order to do action C

My question is: if (/* condition A */) { if(/* condition B */) { /* do action C */ } else /* ... */ } else { /* do action C */ } Is it possible to just write the code of action C one time instead of twice? How…
starf15h
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Determining if a variable is within range?

I need to write a loop that does something like: if i (1..10) do thing 1 elsif i (11..20) do thing 2 elsif i (21..30) do thing 3 etc... But so far have gone down the wrong paths in terms of syntax.
btw
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Can I use conditional statements with EJS templates (in JMVC)?

and if yes, what is the syntax? My goal is to prepend an 's' to the word 'comment' when there is more than one. in an jQuery.ejs template in a JMVC app. The following breaks. I can't find any docs for conditionals... <%=commentsNumber%> comment<% if…
Regis Zaleman
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Inline conditions in Lua (a == b ? "yes" : "no")?

Is there anyway to use inline conditions in Lua? Such as: print("blah: " .. (a == true ? "blah" : "nahblah"))
Softnux
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Set value of one Pandas column based on value in another column

I need to set the value of one column based on the value of another in a Pandas dataframe. This is the logic: if df['c1'] == 'Value': df['c2'] = 10 else: df['c2'] = df['c3'] I am unable to get this to do what I want, which is to simply…
NLR
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Conditional with statement in Python

Is there a way to begin a block of code with a with statement, but conditionally? Something like: if needs_with(): with get_stuff() as gs: # do nearly the same large block of stuff, # involving gs or not, depending on needs_with() To clarify,…
norman
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JavaScript: using a condition in switch case

How can I use a condition inside a switch statement for JavaScript? In the example below, a case should match when the variable liCount is <= 5 and > 0; however, my code does not work: switch (liCount) { case 0: setLayoutState("start"); …
haemse
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Replacing Numpy elements if condition is met

I have a large numpy array that I need to manipulate so that each element is changed to either a 1 or 0 if a condition is met (will be used as a pixel mask later). There are about 8 million elements in the array and my current method takes too long…
ChrisFro
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IF... OR IF... in a windows batch file

Is there a way to write an IF OR IF conditional statement in a windows batch-file? For example: IF [%var%] == [1] OR IF [%var%] == [2] ECHO TRUE
Anthony Miller
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IN Clause with NULL or IS NULL

Postgres is the database Can I use a NULL value for a IN clause? example: SELECT * FROM tbl_name WHERE id_field IN ('value1', 'value2', 'value3', NULL) I want to limit to these four values. I have tried the above statement and it doesn't work, well…
Phill Pafford
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