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Computed / calculated / virtual / derived columns in PostgreSQL
...l, but makes makes life a bit easier).
Suppose my computation is md5(some_string_field), then I create the index as:
CREATE INDEX some_string_field_md5_index ON some_table(MD5(some_string_field));
Now, any queries that act on MD5(some_string_field) will use the index rather than computing it fr...
Differences between Perl and PHP [closed]
...uding matching (=~, !~), quote-like (qw, qx &c.), exponentiation (**), string repetition (x) and range (.. and ...). PHP has a few operators Perl doesn't, such as the error suppression operator (@), instanceof (though Perl does have the Universal::isa method) and clone.
In PHP, new is an operat...
How do I write outputs to the Log in Android?
...ery long. You can define somewhere in your class:
private static final String TAG = "myApp";
and use it when debugging
Log.v(TAG, "did something");
You can apply as well a Filter to only search for the tag.
sha...
Does java have a int.tryparse that doesn't throw an exception for bad data? [duplicate]
C# has Int.TryParse: Int32.TryParse Method (String, Int32%)
3 Answers
3
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Capitalize the first letter of both words in a two word string
Let's say that I have a two word string and I want to capitalize
both of them.
12 Answers
...
KeyValuePair VS DictionaryEntry
...expand on Chris' example (in which we have two dictionaries containing <string, int> pairs).
Dictionary<string, int> dict = new Dictionary<string, int>();
foreach (KeyValuePair<string, int> item in dict) {
int i = item.Value;
}
Hashtable hashtable = new Hashtable();
forea...
Setting environment variables on OS X
...;plist version="1.0">
<dict>
<key>Label</key>
<string>osx-env-sync</string>
<key>ProgramArguments</key>
<array>
<string>bash</string>
<string>-l</string>
<string>-c</string>
<string>
...
Android Paint: .measureText() vs .getTextBounds()
...hat measureText calls native_measureText, and getTextBounds calls nativeGetStringBounds, which are native methods implemented in C++.
So you'd continue to study Paint.cpp, which implements both.
native_measureText -> SkPaintGlue::measureText_CII
nativeGetStringBounds -> SkPaintGlue::getStri...
What is the difference between single and double quotes in SQL?
...
Single quotes are used to indicate the beginning and end of a string in SQL. Double quotes generally aren't used in SQL, but that can vary from database to database.
Stick to using single quotes.
That's the primary use anyway. You can use single quotes for a column alias — where yo...
How to store a command in a variable in a shell script?
...ning about the risk of unexpected parsing behavior (even without malicious strings, as in @CharlesDuffy's example). For example, try x='echo $(( 6 * 7 ))' and then eval $x. You might expect that to print "42", but it probably won't. Can you explain why it doesn't work? Can you explain why I said "pr...