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Android - Back button in the title bar
...d:name="com.example.myfirstapp.DisplayMessageActivity"
android:label="@string/title_activity_display_message"
android:parentActivityName="com.example.myfirstapp.MainActivity" >
<!-- Parent activity meta-data to support 4.0 and lower -->
<meta-data
android:name="an...
How to represent multiple conditions in a shell if statement?
...
Be careful if you have spaces in your string variables and you check for existence. Be sure to quote them properly.
if [ ! "${somepath}" ] || [ ! "${otherstring}" ] || [ ! "${barstring}" ] ; then
...
Create an empty data.frame
... File=character(),
User=character(),
stringsAsFactors=FALSE)
Here's an other example with different column types :
df <- data.frame(Doubles=double(),
Ints=integer(),
Factors=factor(),
Logicals=logical()...
How do I get the difference between two Dates in JavaScript?
...ht do addition, coercion to number or concatenation. Since Dates coerce to String in this case, + does concatenation. Confusion is not the fault of the Date object, but of overloading operators.
– RobG
Mar 22 '16 at 23:53
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What is for Python what 'explode' is for PHP?
I had a string which is stored in a variable myvar = "Rajasekar SP" . I want to split it with delimiter like we do using explode in PHP.
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Unix command to find lines common in two files
...thing in 1.txt will be interpreted as a regular expression and not a plain string. Also, any blank line in 1.txt will match all lines in 2.txt. So grep will only work in very specific situations. You'd at least want to use fgrep (or grep -f) but the blank-line thing is probably going to wreak havoc ...
Difference between sh and bash
...-argument for((i=0;i<=3;i++)) loop, += increment assignment, etc. The $'string\nwith\tC\aescapes' feature is tentatively accepted for POSIX (meaning it works in Bash now, but will not yet be supported by sh on systems which only adhere to the current POSIX specification, and likely will not for s...
Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?
...w Integer[1];
arr[0] = "Hello, there!";
We just assigned a value of type String to an array of type Integer[]. For reasons which should be obvious, this is bad news. Java's type system actually allows this at compile time. The JVM will "helpfully" throw an ArrayStoreException at runtime. Scala...
Differences between ExpandoObject, DynamicObject and dynamic
...class MyNoCookiesInTheJarDynamicObject : DynamicObject
{
Dictionary<string, object> properties = new Dictionary<string, object>();
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
if (properties.ContainsKey(binder.Name))
{
...
How to tell if a file is git tracked (by shell exit code)?
...in a script, for example PowerShell:
$gitResult = (git ls-files $_) | out-string
if ($gitResult.length -ne 0)
{
## do stuff with the tracked file
}
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