Tutorial by Examples: t

If you need to use the ^ character in a character class (Character classes ), either put it somewhere other than the beginning of the class: [12^3] Or escape the ^ using a backslash \: [\^123] If you want to match the caret character itself outside a character class, you need to escape it: ...

Signal numbers can be synchronous (like SIGSEGV – segmentation fault) when they are triggered by a malfunctioning of the program itself or asynchronous (like SIGINT - interactive attention) when they are initiated from outside the program, e.g by a keypress as Cntrl-C. The signal() function is part...

To conditionally include a block of code, the preprocessor has several directives (e.g #if, #ifdef, #else, #endif, etc). /* Defines a conditional `printf` macro, which only prints if `DEBUG` * has been defined */ #ifdef DEBUG #define DLOG(x) (printf(x)) #else #define DLOG(x) #endif Norm...

The simplest form of macro replacement is to define a manifest constant, as in #define ARRSIZE 100 int array[ARRSIZE]; This defines a function-like macro that multiplies a variable by 10 and stores the new value: #define TIMES10(A) ((A) *= 10) double b = 34; int c = 23; TIMES10(b); //...

If the preprocessor encounters an #error directive, compilation is halted and the diagnostic message included is printed. #define DEBUG #ifdef DEBUG #error "Debug Builds Not Supported" #endif int main(void) { return 0; } Possible output: $ gcc error.c error.c: error: #e...

Swift's built-in numeric types are: Word-sized (architecture-dependent) signed Int and unsigned UInt. Fixed-size signed integers Int8, Int16, Int32, Int64, and unsigned integers UInt8, UInt16, UInt32, UInt64. Floating-point types Float32/Float, Float64/Double, and Float80 (x86-only). Literal...

func doSomething1(value: Double) { /* ... */ } func doSomething2(value: UInt) { /* ... */ } let x = 42 // x is an Int doSomething1(Double(x)) // convert x to a Double doSomething2(UInt(x)) // convert x to a UInt Integer initializers produce a runtime error if the value ove...

Use String initializers for converting numbers into strings: String(1635999) // returns "1635999" String(1635999, radix: 10) // returns "1635999" String(1635999, radix: 2) // returns "110001111011010011111&...

The searched CASE returns results when a boolean expression is TRUE. (This differs from the simple case, which can only check for equivalency with an input.) SELECT Id, ItemId, Price, CASE WHEN Price < 10 THEN 'CHEAP' WHEN Price < 20 THEN 'AFFORDABLE' ELSE 'EXPENSIVE' E...

Indexes can have several characteristics that can be set either at creation, or by altering existing indexes. CREATE CLUSTERED INDEX ix_clust_employee_id ON Employees(EmployeeId, Email); The above SQL statement creates a new clustered index on Employees. Clustered indexes are indexes that dict...

UPDATE Customers SET Email = "[email protected]" WHERE id = 1; This will fail if an unique index is set on the Email column of Customers. However, alternate behavior can be defined for this case: UPDATE Customers SET Email = "[email protected]" WHERE id = 1 ON DUP...

Classes are reference types, meaning that multiple variables can refer to the same instance. class Dog { var name = "" } let firstDog = Dog() firstDog.name = "Fido" let otherDog = firstDog // otherDog points to the same Dog instance otherDog.name = "Rover" // modifying otherDog also...

Classes can define properties that instances of the class can use. In this example, Dog has two properties: name and dogYearAge: class Dog { var name = "" var dogYearAge = 0 } You can access the properties with dot syntax: let dog = Dog() print(dog.name) print(dog.dogYear...

Templating can also be applied to functions (as well as the more traditional structures) with the same effect. // 'T' stands for the unknown type // Both of our arguments will be of the same type. template<typename T> void printSum(T add1, T add2) { std::cout << (add1 + add2) &...

var date1 = new Date(); date1.toJSON(); Returns: "2016-04-14T23:49:08.596Z"

Factorials can be computed at compile-time using template metaprogramming techniques. #include <iostream> template<unsigned int n> struct factorial { enum { value = n * factorial<n - 1>::value }; }; template<> struct factorial<0> { ...

WScript.Echo "Hello world!" This displays a message on the console if run with cscript.exe (the console host) or in a message box if run with wscript.exe (the GUI host). If you're using VBScript as the server-side scripting language for a web page (for classic ASP, for example), Respo...

In MATLAB, the most basic data type is the numeric array. It can be a scalar, a 1-D vector, a 2-D matrix, or an N-D multidimensional array. % a 1-by-1 scalar value x = 1; To create a row vector, enter the elements inside brackets, separated by spaces or commas: % a 1-by-4 row vector v = [1, 2...

Composer generates a vendor/autoload.php file. You might simply include this file and you will get autoloading for free. require __DIR__ . '/vendor/autoload.php'; This makes working with third-party dependencies very easy. You can also add your own code to the Autoloader by adding an autoload ...

Swift let label = UILabel() Objective-C UILabel *label = [[UILabel alloc] init]; or UILabel *label = [UILabel new]; // convenience method for calling alloc-init Change the default font's size Swift label.font = UIFont.systemFontOfSize(17) Swift 3 label.font = UIFont.systemFont(ofSi...