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How to terminate the script in JavaScript?
How can I exit the JavaScript script much like PHP's exit or die ? I know it's not the best programming practice but I need to.
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How to tell if a string is not defined in a Bash shell script
...guish whether VAR is set but empty or not set, you can use:
if [ -z "${VAR+xxx}" ]; then echo VAR is not set at all; fi
if [ -z "$VAR" ] && [ "${VAR+xxx}" = "xxx" ]; then echo VAR is set but empty; fi
You probably can combine the two tests on the second line into one with:
if [ -z "$VAR" -a...
二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...下二维码一共有40个尺寸。官方叫版本Version。Version 1是21 x 21的矩阵，Version 2是 25 x 25的矩阵，Version 3是29的尺寸，每增加一个version，就会增加4的尺寸，公式是：(V-1)*4 + 21（V是版本号） 最高Version 40，(40-1)*4+21 = 177，所以最高是177...
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...
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...
JSON.parse vs. eval()
...n.parse just parses JSON whereas eval would leave the door open to all JS expressions.
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Appending a line to a file only if it does not already exist
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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...
How to truncate string using SQL server
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If col is exactly 15 in length it will get the entire string when doing left(col,15) and then put '...' on the end. Surely a better solution is checking 'when len(col) > 15'.
– Murphybro2
Dec 6 ...
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 can I reliably determine the type of a variable that is declared using var at design time?
...ween keystrokes.
When the IDE needs to work out the type of a particular expression inside a method body -- say you've typed "foo." and we need to figure out what are the members of foo -- we do the same thing; we skip as much work as we reasonably can.
We start with a pass which analyzes only th...