Tutorial by Examples: io

Considering the following users table: idusername1User12User23User34User45User5 In order to constrain the number of rows in the result set of a SELECT query, the LIMIT clause can be used together with one or two positive integers as arguments (zero included). LIMIT clause with one argument When ...

One use case for assertion is precondition and postcondition. This can be very useful to maintain invariant and design by contract. For a example a length is always zero or positive so this function must return a zero or positive value. #include <stdio.h> /* Uncomment to disable `assert()`...

The following C source file (which we will call hello.c for demonstration purposes) produces an extension module named hello that contains a single function greet(): #include <Python.h> #include <stdio.h> #if PY_MAJOR_VERSION >= 3 #define IS_PY3K #endif static PyObject *hell...

You can overload type operators, so that your type can be implicitly converted into the specified type. The conversion operator must be defined in a class/struct: operator T() const { /* return something */ } Note: the operator is const to allow const objects to be converted. Example: struct ...

You can overload the function call operator (): Overloading must be done inside of a class/struct: //R -> Return type //Types -> any different type R operator()(Type name, Type2 name2, ...) { //Do something //return something } //Use it like this (R is return type, a and b a...

This method can be used to convert a formatted string representation of a date into a Date object. /** * Parses the date using the given format. * * @param formattedDate the formatted date string * @param dateFormat the date format which was used to create the string. ...

An assertion is a statement used to assert that a fact must be true when that line of code is reached. Assertions are useful for ensuring that expected conditions are met. When the condition passed to an assertion is true, there is no action. The behavior on false conditions depends on compiler fl...

C11 Static assertions are used to check if a condition is true when the code is compiled. If it isn't, the compiler is required to issue an error message and stop the compiling process. A static assertion is one that is checked at compile time, not run time. The condition must be a constant expres...

To find files/directories with a specific name, relative to pwd: $ find . -name "myFile.txt" ./myFile.txt To find files/directories with a specific extension, use a wildcard: $ find . -name "*.txt" ./myFile.txt ./myFile2.txt To find files/directories matching one of ma...

A lambda expression provides a concise way to create simple function objects. A lambda expression is a prvalue whose result object is called closure object, which behaves like a function object. The name 'lambda expression' originates from lambda calculus, which is a mathematical formalism invented...

On an ext filesystem, each file has a stored Access, Modification, and (Status) Change time associated with it - to view this information you can use stat myFile.txt; using flags within find, we can search for files that were modified within a certain time range. To find files that have been modifi...

To encode a string into a byte array, you can simply use the String#getBytes() method, with one of the standard character sets available on any Java runtime: byte[] bytes = "test".getBytes(StandardCharsets.UTF_8); and to decode: String testString = new String(bytes, StandardCharsets.U...

Functions can return tuples: func tupleReturner() -> (Int, String) { return (3, "Hello") } let myTuple = tupleReturner() print(myTuple.0) // 3 print(myTuple.1) // "Hello" If you assign parameter names, they can be used from the return value: func tupleReturner(...

Browse to File > New > Solution to bring you up the new project dialog. Select Android App and press Next. Configure your app by setting your app name and organization ID. Select the Target Platform most suited for your needs, or leave it as the default. Press Next: Set your Project name ...

Browse to File > New > Project to bring you up the New Project dialog. Navigate to Visual C# > Android and select Blank App: Give your app a Name and press OK to create your project. Set up your device for deployment, or configure an emulator To run your application, select the Debug...

Here is an example of a Bosun config file used in a development environment: tsdbHost = localhost:4242 httpListen = :8070 smtpHost = localhost:25 emailFrom = [email protected] timeAndDate = 202,75,179,136 ledisDir = ../ledis_data checkFrequency = 5m notification example.notification { ...

All instances of Preferences are always thread-safe across the threads of a single Java Virtual Machine (JVM). Because Preferences can be shared across multiple JVMs, there are special methods that deal with synchronizing changes across virtual machines. If you have an application which is supposed...

A very common guideline in object oriented design is "as little as possible but as much as necessary". This also applies to the strategy pattern: It is usually advisable to hide implementation details, for example which classes actually implement strategies. For simple strategies which do...

Iterators and pointers pointing into an std::vector can become invalid, but only when performing certain operations. Using invalid iterators/pointers will result in undefined behavior. Operations which invalidate iterators/pointers include: Any insertion operation which changes the capacity of...

Useful for simple animations, the CSS transition property allows number-based CSS properties to animate between states. Example .Example{ height: 100px; background: #fff; } .Example:hover{ height: 120px; background: #ff0000; } View Result By default, hovering over an...