Tutorial by Examples: ar

In this example database for a library, we have Authors, Books and BooksAuthors tables. Live example: SQL fiddle Authors and Books are known as base tables, since they contain column definition and data for the actual entities in the relational model. BooksAuthors is known as the relationship tabl...

NSDictionary *myDictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"value1", @"key1", @"value2", @"key2", nil]; NSArray *copiedArray = myDictionary.copy; Get keys: NSArray *keys = [myDictionary allKeys]; Get values: NSArray *values = [myDic...

NSDictionary *myDictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"value1", @"key1", @"value2", @"key2", nil]; NSData *myData = [NSKeyedArchiver archivedDataWithRootObject:myDictionary]; Reserve path: NSDictionary *myDictionary = (NSDictionary*...

NSDictionary *myDictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"value1", @"key1", @"value2", @"key2", nil]; NSMutableDictionary *mutableDictionary = [myDictionary mutableCopy]; NSData *data = [NSJSONSerialization dataWithJSONObject:myDiction...

//Swift let barButtonItem = UIBarButtonItem(title: "Greetings!", style: .Plain, target: self, action: #selector(barButtonTapped)) self.navigationItem.rightBarButtonItem = barButtonItem //Objective-C UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Greeti...

[a-b] where a and b are digits in the range 0 to 9 [3-7] will match a single digit in the range 3 to 7. Matching multiple digits \d\d will match 2 consecutive digits \d+ will match 1 or more consecutive digits \d* will match 0 or more consecutive digits \d{3} will ma...

NSSet *set = [NSSet set]; NSArray *array = [NSArray array]; NSArray *fromSet = [set allObjects]; NSSet *fromArray = [NSSet setWithArray:array];

Tuples can be compared based on their elements. As an example, an enumerable whose elements are of type Tuple can be sorted based on comparisons operators defined on a specified element: List<Tuple<int, string>> list = new List<Tuple<int, string>>(); list.Add(new Tuple<...

References behaves similarly, but not entirely like const pointers. A reference is defined by suffixing an ampersand & to a type name. int i = 10; int &refi = i; Here, refi is a reference bound to i. References abstracts the semantics of pointers, acting like an alias to the underlying...

The strchr and strrchr functions find a character in a string, that is in a NUL-terminated character array. strchr return a pointer to the first occurrence and strrchr to the last one. #include <stdio.h> #include <stdlib.h> #include <string.h> int main(void) { char toSe...

ALTER TABLE EMPLOYEES ADD pk_EmployeeID PRIMARY KEY (ID) This will add a Primary key to the table Employees on the field ID. Including more than one column name in the parentheses along with ID will create a Composite Primary Key. When adding more than one column, the column names must be separat...

countMatches method from org.apache.commons.lang3.StringUtils is typically used to count occurences of a substring or character in a String: import org.apache.commons.lang3.StringUtils; String text = "One fish, two fish, red fish, blue fish"; // count occurrences of a substring Str...

Scalars are Perl's most basic data type. They're marked with the sigil $ and hold a single value of one of three types: a number (3, 42, 3.141, etc.) a string ('hi', "abc", etc.) a reference to a variable (see other examples). my $integer = 3; # number my $str...

Arrays store an ordered sequence of values. You can access the contents by index, or iterate over them. The values will stay in the order you filled them in. my @numbers_to_ten = (1,2,3,4,5,6,7,8,9,10); # More conveniently: (1..10) my @chars_of_hello = ('h','e','l','l','o'); my @word_list = ('Hel...

The following code demonstrates usage of arc4random_uniform() to generate a random integer between 3 and 12: uint32_t randomIntegerWithinRange = arc4random_uniform(10) + 3; // A random integer between 3 and 12 This works to create a range because arc4random_uniform(10) returns an integer between...

hash( (1, 2) ) # ok hash( ([], {"hello"}) # not ok, since lists and sets are not hashabe Thus a tuple can be put inside a set or as a key in a dict only if each of its elements can. { (1, 2) } # ok { ([], {"hello"}) ) # not ok

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'if only one area (not multiple areas): With Range("A3:D20") Debug.Print .Cells(.Cells.CountLarge).Row Debug.Print .Item(.Cells.CountLarge).Row 'using .item is also possible End With 'Debug prints: 20 'with multiple areas (also works if only one area): Dim rngArea As Range,...

In Python 3.x all classes are new-style classes; when defining a new class python implicitly makes it inherit from object. As such, specifying object in a class definition is a completely optional: Python 3.x3.0 class X: pass class Y(object): pass Both of these classes now contain object in ...

To start with multi-threading, you would need the pthreads-ext for php, which can be installed by $ pecl install pthreads and adding the entry to php.ini. A simple example: <?php // NOTE: Code uses PHP7 semantics. class MyThread extends Thread { /** * @var string * Variab...