Tutorial by Examples: an

Sometimes you want to have a file held in Git but ignore subsequent changes. Tell Git to ignore changes to a file or directory using update-index: git update-index --assume-unchanged my-file.txt The above command instructs Git to assume my-file.txt hasn't been changed, and not to check or repor...

Starting the Erlang shell On a UNIX system you start the Erlang shell from a command prompt with the command erl Example: $ erl Erlang/OTP 18 [erts-7.0] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] Eshell V7.0 (abort with ^G) 1> The text that shows when y...

Quantitative data is often read in as strings that must be converted to numeric types before processing. The types of all list items can be converted with either a List Comprehension or the map() function. # Convert a list of strings to integers. items = ["1","2","3",...

A deadlock is what occurs when two or more threads are waiting for eachother to complete or to release a resource in such a way that they wait forever. If thread1 holds a lock on resource A and is waiting for resource B to be released while thread2 holds resource B and is waiting for resource A to ...

To draw a vector SVG image, the operation is not different from a raster image : You first need to load your SVG image into an HTMLImage element, then use the drawImage() method. var image = new Image(); image.onload = function(){ ctx.drawImage(this, 0,0); } image.src = "someFile.SVG&...

Current updates the branch on the remote repository that shares a name with the current working branch. git config push.default current Simple pushes to the upstream branch, but will not work if the upstream branch is called something else. git config push.default simple Upstream pushes to t...

This is the basic way to insert data from another table with the SELECT statement. INSERT INTO `tableA` (`field_one`, `field_two`) SELECT `tableB`.`field_one`, `tableB`.`field_two` FROM `tableB` WHERE `tableB`.clmn <> 'someValue' ORDER BY `tableB`.`sorting_clmn`; You can...

We can change the style of the placeholder by setting attributedPlaceholder (a NSAttributedString). var placeholderAttributes = [String: AnyObject]() placeholderAttributes[NSForegroundColorAttributeName] = color placeholderAttributes[NSFontAttributeName] = font if let placeholder = textField.p...

If you need to clean the build: ndk-build clean

Starting a File Chooser Activity public void showFileChooser() { Intent intent = new Intent(Intent.ACTION_GET_CONTENT); // Update with mime types intent.setType("*/*"); // Update with additional mime types here using a String[]. intent.putExtra(Intent.EXTRA_M...

os.chmod(path, mode) where mode is the desired permission, in octal.

Create a DATABASE. Note that the shortened word SCHEMA can be used as a synonym. CREATE DATABASE Baseball; -- creates a database named Baseball If the database already exists, Error 1007 is returned. To get around this error, try: CREATE DATABASE IF NOT EXISTS Baseball; Similarly, DROP DATA...

class ClassWithAReallyLongName { public: class Iterator { /* ... */ }; Iterator end(); }; Defining the member end with a trailing return type: auto ClassWithAReallyLongName::end() -> Iterator { return Iterator(); } Defining the member end without a trailing return type: Clas...

>>> df ID Year Jan_salary Feb_salary Mar_salary 0 1 2016 4500 4200 4700 1 2 2016 3800 3600 4400 2 3 2016 5500 5200 5300 >>> melted_df = pd.melt(df,id_vars=['ID','Year'], v...

Navigation Drawers are used to navigate to top-level destinations in an app. Make sure that you have added design support library in your build.gradle file under dependencies: dependencies { // ... compile 'com.android.support:design:25.3.1' } Next, add the DrawerLayout and Navigati...

Comments are used to explain code when the basic code itself isn't clear. Python ignores comments, and so will not execute code in there, or raise syntax errors for plain english sentences. Single-line comments begin with the hash character (#) and are terminated by the end of line. Single lin...

auto can also cause problems where expression templates come into play: auto mult(int c) { return c * std::valarray<int>{1}; } auto v = mult(3); std::cout << v[0]; // some value that could be, but almost certainly is not, 3. The reason is that operator* on valarray gives yo...

Using range-base loops, you can loop over a sub-part of a given container or other range by generating a proxy object that qualifies for range-based for loops. template<class Iterator, class Sentinel=Iterator> struct range_t { Iterator b; Sentinel e; Iterator begin() const { return ...

Given the following XML document: <documentation> <tags> <tag name="Java"> <topic name="Regular expressions"> <example>Matching groups</example> <example>Escaping metacharacter...

Sometimes specific instances of data should be used. Recreation is not desired and referencing static data would have a code smell. It is possible to specify a XmlAdapter instance the Unmarshaller should use, which allows the user to use XmlAdapters with no zero-arg constructor and/or pass data to ...