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What does an exclamation mark mean in the Swift language?
...ome/None), not the value itself (T). So john isn't an instance of Person, and it doesn't have an apartment member:
john.apartment
// 'Person?' does not have a member named 'apartment'
The actual Person value can be unwrapped in various ways:
"forced unwrapping": john! (gives the Person value i...
CSV API for Java [closed]
...ill allow me to use read a CSV input file, do some simple transformations, and then write it.
10 Answers
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How can I use grep to find a word inside a folder?
... a specific word occurs inside a directory containing many sub-directories and files. My searches for grep syntax shows I must specify the filename, i.e. grep string filename .
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What's the difference of ContentType and MimeType
...e same) thing? Is
"Content-Type" just a name used in
browser requests, and with very little
use outside it?
What's the main difference between the
each one, and when is right to call
something mimetype as opposed to
content-type ? Am i being pitty and
grammar nazi?
The reason is...
Fast permutation -> number -> permutation mapping algorithms
...you have n possibilities, so you can describe this with a number between 0 and n-1. For the position that the next element ends up at, you have n-1 remaining possibilities, so you can describe this with a number between 0 and n-2.
Et cetera until you have n numbers.
As an example for n = 5, consid...
Extract source code from .jar file
...
Use JD GUI. Open the application, drag and drop your JAR file into it.
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In Python, what is the difference between “.append()” and “+= []”?
...d will add one item to the list, while += will copy all elements of right-hand-side list into the left-hand-side list.
Update: perf analysis
Comparing bytecodes we can assume that append version wastes cycles in LOAD_ATTR + CALL_FUNCTION, and += version -- in BUILD_LIST. Apparently BUILD_LIST outw...
Ruby: require vs require_relative - best practice to workaround running in both Ruby =1.
What is the best practice if I want to require a relative file in Ruby and I want it to work in both 1.8.x and >=1.9.2?
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Variable declaration placement in C
...on of s as a GNU extension, even though it's not part of the C89 or ANSI standard. If you want to adhere strictly to those standards, you must pass the -pedantic flag.
The declaration of c at the start of a { } block is part of the C89 standard; the block doesn't have to be a function.
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Java regex capturing groups indexes
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Capturing and grouping
Capturing group (pattern) creates a group that has capturing property.
A related one that you might often see (and use) is (?:pattern), which creates a group without capturing property, hence named non-capturi...