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Articles by Ankith Reddy
Page 47 of 73
How to assign multiple values to a same variable in Python?
In Python, if you try to do something likea = b = c = [0,3,5] a[0] = 10You'll end up with the same values ina, b, and c: [10, 3, 5]This is because all three variables here point to the same value. If you modify this value, you'll get the change reflected in all names, ie, a,b and c. To create a new object and assign it, you can use the copy module. examplea = [0,3,5] import copy b = copy.deepcopy(a) a[0] = 5 print(a) print(b)OutputThis will give the output −[5,3,5] [0,3,5]
Read MoreWhy should C++ programmers minimize use of 'new'?
new is used for dynamic memory allocation. The memory allocated in this case goes on the heap. There are several costs associated with this type of memory allocation along with the programmer having to do manual memory cleaning and management. This type of allocation must be used when − You don't know how much memory you need at compile time.You want to allocate memory which will persist after leaving the current block.Other than these, there are very few cases where dynamic memory allocation is required. This is because, in C++, there is the concept of a destructor. This function gets called ...
Read MoreWhat should be the order in which libraries are linked in GCC?
The linker searches from left to right. While doing so it encounters unresolved symbols which it keeps track of. If a library resolves the unresolved symbol, it takes the object files of that library to resolve the symbol.Dependencies of static libraries from each other work in the same way. Libraries requiring symbols from other library come before libraries resolving the symbol. If you have cyclic dependencies, you must enclose the libraries having a cyclic dependency in parenthesis. For example, if you have libraries a and b that are cyclically dependent −$ g++ hello.cpp -L. -( -la -lb -)Newer linkers are ...
Read MoreSorting a vector of custom objects using C++ STL
You can sort a vector of custom objects using the C++ STL function std::sort. The sort function has an overloaded form that takes as arguments first, last, comparator. The first and last are iterators to first and last elements of the container. The comparator is a predicate function that can be used to tell how to sort the container. example#include #include #include using namespace std; struct MyStruct { int key; string data; MyStruct(int key, string data) { this -> key = key; this -> data = data; } }; int ...
Read MoreHow can I use SPACE() function with MySQL WHERE clause?
In this case, SPACE() function would add white spaces depending upon the condition given in WHERE clause. The following example from student table will demonstrate it.Examplemysql> Select Id,Name,Space(5) from student WHERE Name='Harshit'; +------+---------+----------+ | Id | Name | Space(5) | +------+---------+----------+ | 15 | Harshit | | +------+---------+----------+ 1 row in set (0.00 sec)
Read MoreWhat MySQL returns if the argument of QUOTE() function is NULL?
MySQL returns NULL if the argument of QUOTE() function is NULL.Examplemysql> Select QUOTE(NULL); +-------------+ | QUOTE(NULL) | +-------------+ | NULL +-------------+ 1 row in set (0.00 sec) mysql> Select Name, QUOTE(NULL) from student where id = 1; +--------+-------------+ | Name | QUOTE(NULL) | +--------+-------------+ | Gaurav | NULL | +--------+-------------+ 1 row in set (0.08 sec)
Read MoreIn MySQL, how can we check whether a string of a specified pattern is not present within another string?
We can check whether a string of specified pattern is not present within another string by using NOT LIKE operator along with wildcard characters.SyntaxNOT LIKE specific_patternSpecific_pattern is the pattern of string we do not want to find out within another string.ExampleSuppose we have a table named ‘student’ having names of the students and we want to get the details of all those students which are not having a pattern of string ‘av’ within their names. It can be done with the help of following MySQL query:mysql> Select * from Student WHERE name NOT LIKE '%av%'; +------+---------+---------+----------+--------------------+ | Id ...
Read MoreHow can we use LPAD() or RPAD() functions with the values in the column of a MySQL table?
For using LPAD() or RPAD() functions with the column values we need to specify the column name as the first argument of these functions. Following the example from ‘Student’ table will make it clearer −Examplemysql> Select Name, LPAD(Name, 10, '*') from student; +---------+-------------------+ | Name | LPAD(Name, 10, '*') | +---------+-------------------+ | Gaurav | ****Gaurav | | Aarav | *****Aarav | | Harshit | ***Harshit | | Gaurav | ****Gaurav ...
Read MoreWhat is the significance of using multiple columns in MySQL GROUP BY clause?
By specifying multiple columns in GROUP BY clause we can split the result set into smaller groups. The more columns specified in GROUP BY clause, the smaller the groups will be.Examplemysql> Select designation, YEAR(Doj), count(*) from employees GROUP BY designation, YEAR(DoJ); +-------------+-----------+----------+ | designation | YEAR(Doj) | count(*) | +-------------+-----------+----------+ | Asso.Prof | 2013 | 1 | | Asst.Prof | 2015 | 1 | | Asst.Prof | 2016 | 1 | | Prof | 2009 | 2 | | Prof | 2010 | 1 | +-------------+-----------+----------+ 5 rows in set (0.00 sec)
Read MoreWhy we cannot use comparison operator(=) for getting the rows with NULL from a table?
We cannot use = (comparison operator) because we know that NULL is not a value. If we want to get the rows with NULL from a table then we need to use IS NULL operator in MySQL query. Following example using the data from ‘employee’ table will exhibit it −Examplemysql> Select * from Employee WHERE Salary IS NULL; +----+-------+--------+ | ID | Name | Salary | +----+-------+--------+ | 7 | Aryan | NULL | | 8 | Vinay | NULL | +----+-------+--------+ 2 rows in set (0.00 sec)The query above use IS NULL operator and produces ...
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