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Articles on Trending Technologies
Technical articles with clear explanations and examples
Base Overloading Methods in Python
Following table lists some generic functionality that you can override in your own classes −Sr.No.Method, Description & Sample Call1__init__ ( self [,args...] )Constructor (with any optional arguments)Sample Call : obj = className(args)2__del__( self )Destructor, deletes an objectSample Call : del obj3__repr__( self )Evaluable string representationSample Call : repr(obj)4__str__( self )Printable string representationSample Call : str(obj)5__cmp__ ( self, x )Object comparisonSample Call : cmp(obj, x)
Read MoreStyle Rules in CSS
CSS comprises of style rules interpreted by the browser and then applied to the corresponding elements in your document. A style rule is made of three parts −Selector - A selector is an HTML tag at which a style will be applied. This could be any tag like or etc.Property - A property is a type of attribute of HTML tag. Put simply, all the HTML attributes are converted into CSS properties. They could be color, border etc.Value - Values assigned to properties. For example, the color property can have value either red or #F1F1F1 etcYou can put CSS Style Rule Syntax as ...
Read MoreUniversal Selectors in CSS
A selector is an HTML tag at which a style will be applied. This could be any tag like or etc.With the type selector, set for HTML tags like h1, h2, h3, p, etc:h2 { color: #FFFF00; }Rather than selecting elements of a specific type, the universal selector simply matches the name of any element type:* { color: #FFFF00; }
Read MoreComparison of CSS versions
Cascading Style Sheets, level 1 (CSS1) was came out of W3C as a recommendation in December 1996. This version describes the CSS language as well as a simple visual formatting model for all the HTML tags.CSS2 became a W3C recommendation in May 1998 and builds on CSS1. This version adds support for media-specific style sheets e.g. printers and aural devices, downloadable fonts, element positioning, and tables.CSS3 became a W3C recommendation in June 1999 and builds on older versions CSS. it has divided into documentation is called as Modules and here each module having new extension features defined in CSS2.CSS3 is ...
Read MoreOverloading Operators in Python
Suppose you have created a Vector class to represent two-dimensional vectors, what happens when you use the plus operator to add them? Most likely Python will yell at you.You could, however, define the __add__ method in your class to perform vector addition and then the plus operator would behave as per expectation −Example Live Demo#!/usr/bin/python class Vector: def __init__(self, a, b): self.a = a self.b = b def __str__(self): return 'Vector (%d, %d)' % (self.a, self.b) def __add__(self, other): return Vector(self.a + other.a, self.b + other.b) v1 = ...
Read MoreHow can CONCAT() function be applied on columns of MySQL table?
We can use CONCAT() function to combine the values of two or more columns. In this case, the arguments of the CONCAT() functions would be the name of the columns. For example, suppose we have a table named ‘Student’ and we want the name and address of the student collectively in one column then the following query can be written −mysql> Select Id, Name, Address, CONCAT(ID, ', ', Name, ', ', Address)AS 'ID, Name, Address' from Student; +------+---------+---------+--------------------+ | Id | Name | Address | ID, Name, Address | +------+---------+---------+--------------------+ | 1 | Gaurav | Delhi ...
Read MoreHow can CONCAT() function be used with MySQL WHERE clause?
Suppose from the table ‘Student’ we want to concatenate the values of columns, ‘Name’, ‘Address’ and ‘Columns’, based on the condition that is also a concatenation of values from columns, ’Name’, ‘Subject’, provided in WHERE clause with the help of CONCAT() function. We can use the following query to give the output −mysql> Select CONCAT(Name, ' ', 'Resident of', ' ', Address, ' ', 'is', ' ', 'Studying', ' ', Subject)AS 'Detail of Student' from Student WHERE CONCAT(Name, Subject) = "AaravHistory"; +----------------------------------------------+ | Detail of Student | ...
Read MoreDestroying Objects (Garbage Collection) in Python
Python deletes unneeded objects (built-in types or class instances) automatically to free the memory space. The process by which Python periodically reclaims blocks of memory that no longer are in use is termed Garbage Collection.Python's garbage collector runs during program execution and is triggered when an object's reference count reaches zero. An object's reference count changes as the number of aliases that point to it changes.An object's reference count increases when it is assigned a new name or placed in a container (list, tuple, or dictionary). The object's reference count decreases when it's deleted with del, its reference is reassigned, or ...
Read MoreHow Can MySQL CAST handle overflow?
MySQL CAST can handle overflow occurs during numerical expression assessment. Suppose if numeric expression evaluation produces overflow then MySQL reflects an error message. Now to handle this overflow we can change that numeric value to UNSIGNED with the help of CAST.For example on adding 1 to BIGINT maximum value, MySQL produce an error due to overflow as follows −mysql> Select 9223372036854775807 + 1; ERROR 1690 (22003): BIGINT value is out of range in '(9223372036854775807+1)'Now, with the help of CAST, MySQL handles this kind of overflow as follows:mysql> Select CAST(9223372036854775807 AS UNSIGNED) +1; +------------------------------------------+ | CAST(9223372036854775807 AS UNSIGNED) +1 | +------------------------------------------+ | 9223372036854775808 | +------------------------------------------+ 1 row in set (0.07 sec)
Read MoreWhat is the use of NO_UNSIGNED_SUBTRACT SQL mode in handling overflow?
In case of enabled SQL strict mode, subtraction between integers value in which one is of UNSIGNED type will produce an unsigned result by default. But MySQL produces an error if the result is a negative one. It can be observed with the following example −mysql> SET sql_mode = ''; Query OK, 0 rows affected (0.00 sec) mysql> Select CAST(0 AS UNSIGNED) -1; ERROR 1690 (22003): BIGINT UNSIGNED value is out of range in '(cast(0 as unsigned) - 1)'The error after the query above shows that it is an overflow after numeric arithmetic expression.Now, it can be handled with ...
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