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How to check if multiple array keys exists
... check (like in the original question), it's probably easy enough to just call array_key_exists() twice to check if the keys exists.
if (array_key_exists("story", $arr) && array_key_exists("message", $arr)) {
// Both keys exist.
}
However this obviously doesn't scale up well to many k...
Fastest way to check if a file exist using standard C++/C++11/C?
...e thousands of files and before doing something on them I need to check if all of them exist. What can I write instead of /* SOMETHING */ in the following function?
...
Search and replace in bash using regular expressions
...'s are processed in order. Also, the g flag for the expression will match all occurrences in the input.
You can also pick your favorite tool using this method, i.e. perl, awk, e.g.:
echo "$MYVAR" | perl -pe 's/[a-zA-Z]/X/g and s/[0-9]/N/g'
This may allow you to do more creative matches... For ...
How can I get a count of the total number of digits in a number?
...
@Puterdo Borato: my performance test actually showed that your method is faster when the number of digits are < 5. Pass that, Steve's Math.floor is faster.
– stack247
Apr 7 '15 at 22:56
...
Truncate all tables in a MySQL database in one command?
Is there a query (command) to truncate all the tables in a database in one operation? I want to know if I can do this with one single query.
...
Difference between Observer, Pub/Sub, and Data Binding
...
Here's my take on the three:
Data Binding
Essentially, at the core this just means "the value of property X on object Y is semantically bound to the value of property A on object B. No assumptions are made as to how Y knows or is fed changes on object B.
Observer, or Obser...
What is the behavior difference between return-path, reply-to and from?
...
Now, let's describe the different "FROM"s.
The return path (sometimes called the reverse path, envelope sender, or envelope from — all of these terms can be used interchangeably) is the value used in the SMTP session in the MAIL FROM command. As you can see, this does not need to be the same v...
Why does ~True result in -2?
...00000001
and ~1 is:
11111110
Which is -2 in Two's complement1
1 Flip all the bits, add 1 to the resulting number and interpret the result as a binary representation of the magnitude and add a negative sign (since the number begins with 1):
11111110 → 00000001 → 00000010
↑ ...
Omit rows containing specific column of NA
...# 2 2 10 33
EDIT: Only return rows with no NAs
If you want to eliminate all rows with at least one NA in any column, just use the complete.cases function straight up:
DF[complete.cases(DF), ]
# x y z
# 2 2 10 33
Or if completeFun is already ingrained in your workflow ;)
completeFun(DF, na...
Which iomanip manipulators are 'sticky'?
... the comments below:
By Martin:
@Chareles: Then by this requirement all manipulators are sticky. Except setw which seems to be reset after use.
By Charles:
Exactly! and the only reason that setw appears to behave differently is because there are requirements on formatted output operat...