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What is a wrapper class?
...raction from the implementation of the underlying class or component; for example, wrapper classes that wrap COM components can manage the process of invoking the COM component without bothering the calling code with it. They can also simplify the use of the underlying object by reducing the number...
Test for non-zero length string in Bash: [ -n “$var” ] or [ “$var” ]
...ting the contents of the variable as if they were part of the conditional expression (the result matches the assertion implied by the "T" or "F" in the description column). When [[ is used (column 1b), the variable content is seen as a string and not evaluated.
The errors in columns 3a and 5a are c...
Convert to binary and keep leading zeros in Python
...at Specification mini language. The # makes the format include the 0b prefix, and the 010 size formats the output to fit in 10 characters width, with 0 padding; 2 characters for the 0b prefix, the other 8 for the binary digits.
This is the most compact and direct option.
If you are putting the res...
How to write a cron that will run a script every day at midnight?
...--0 minutes and 0 hours--and the *s mean every day of every month.)
Syntax:
mm hh dd mt wd command
mm minute 0-59
hh hour 0-23
dd day of month 1-31
mt month 1-12
wd day of week 0-7 (Sunday = 0 or 7)
command: what you want to run
all numeric values can be replaced by * which mean...
Appending a line to a file only if it does not already exist
...
Just keep it simple :)
grep + echo should suffice:
grep -qxF 'include "/configs/projectname.conf"' foo.bar || echo 'include "/configs/projectname.conf"' >> foo.bar
-q be quiet
-x match the whole line
-F pattern is a plain string
https://linux.die.net/man/1/grep
Edit:
inco...
In PHP, can you instantiate an object and call a method on the same line?
... @CMCDragonkai logically that makes sense; the object only exists for the duration of the statement (new Foo)->property - the value you are storing has nowhere to go because the object will no longer exist after that as it's not stored anywhere.
– thomasrutter...
How to do a non-greedy match in grep?
...ng for a non-greedy (or lazy) match. To get a non-greedy match in regular expressions you need to use the modifier ? after the quantifier. For example you can change .* to .*?.
By default grep doesn't support non-greedy modifiers, but you can use grep -P to use the Perl syntax.
...
Using vagrant to run virtual machines with desktop environment
... development environment is based on virtual machines, running on VirtualBox. We would like to move one step further, and use the capabilities of Vagrant to have the description of the machine in a text file and then be able to "raise" that machine based on that text file. Combined to puppet, this w...
What is the MIME type for Markdown?
Does anyone know if there exists a MIME type for Markdown? I guess it is text/plain , but is there a more specific one?
4 ...
How do I determine the size of my array in C?
...
Executive summary:
int a[17];
size_t n = sizeof(a)/sizeof(a[0]);
Full answer:
To determine the size of your array in bytes, you can use the sizeof
operator:
int a[17];
size_t n = sizeof(a);
On my computer, ints are 4 ...