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Indexes of all occurrences of character in a string
The following code will print 2
14 Answers
14
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NameError: name 'self' is not defined
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Default argument values are evaluated at function define-time, but self is an argument only available at function call time. Thus arguments in the argument list cannot refer each other.
It's a common pattern to default an argument to None and add a test for that in code:
def p(self, b=...
What is an initialization block?
We can put code in a constructor or a method or an initialization block. What is the use of initialization block? Is it necessary that every java program must have it?
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Null coalescing in powershell
... you can use the standard Powershell if statements as an expression:
variable = if (condition) { expr1 } else { expr2 }
So to the replacements for your first C# expression of:
var s = myval ?? "new value";
becomes one of the following (depending on preference):
$s = if ($myval -eq $null) { "n...
XPath to select multiple tags
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One correct answer is:
/a/b/*[self::c or self::d or self::e]
Do note that this
a/b/*[local-name()='c' or local-name()='d' or local-name()='e']
is both too-long and incorrect. This XPath expression will select nodes like:
OhMy:c
NotWanted:d
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How to extract a substring using regex
I have a string that has two single quotes in it, the ' character. In between the single quotes is the data I want.
13 An...
How do I generate random numbers in Dart?
How do I generate random numbers using Dart?
13 Answers
13
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When NOT to call super() method when overriding?
...ustom class, I extend its native class. Then when I want to override the base method, I always call super() method, just like I always do in onCreate , onStop , etc.
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Why does PHP 5.2+ disallow abstract static class methods?
After enabling strict warnings in PHP 5.2, I saw a load of strict standards warnings from a project that was originally written without strict warnings:
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Adding a column to a data.frame
I have the data.frame below. I want to add a column that classifies my data according to column 1 ( h_no ) in that way that the first series of h_no 1,2,3,4 is class 1, the second series of h_no (1 to 7) is class 2 etc. such as indicated in the last column.
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