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Articles on Trending Technologies
Technical articles with clear explanations and examples
Why 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 MoreHow to Swap Two Variables using Python?
By using a temporary variable −>>> x=10 >>> y=20 >>> z=x >>> x=y >>> y=z >>> x,y (20, 10)Without using temporary variable>>> a,b=5,7 >>> a,b (5, 7) >>> a,b=b,a >>> a,b (7, 5)
Read MoreUpdate only a single column value in MySQL
Let us first create a table −mysql> create table DemoTable1605 -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20), -> StudentCountryName varchar(20) -> ); Query OK, 0 rows affected (0.48 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1605(StudentName, StudentCountryName) values('Adam', 'AUS'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable1605(StudentName, StudentCountryName) values('John', 'US'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable1605(StudentName, StudentCountryName) values('Bob', 'UK'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select ...
Read MoreHow to ignore specific records and add remaining corresponding records (numbers) in MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Name varchar(20), -> Amount int -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John', 200); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Chris', 150); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('Mike', 500); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('John', 350); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> ...
Read MoreUpdate with multiple values in MySQL WHERE clause
Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Name varchar(20), -> Age int, -> CountryName varchar(10) -> ); Query OK, 0 rows affected (0.81 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 'Chris', 34, 'AUS'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(101, 'Chris', 31, 'US'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(102, 'David', 25, 'UK'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(103, 'Carol', 28, 'AUS'); ...
Read MoreWorking with WHERE IN() in a MySQL Stored Procedure
Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 'Chris'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(101, 'Bob'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(102, 'David'); Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −mysql> select * from DemoTable;This will produce the following output −+------+-------+ | Id ...
Read MoreHow to sum cells in a column if a condition is met in another column with MySQL?
For this, you can use the aggregate function SUM() along with the GROUP BY clause. Let us first create a table −mysql> create table DemoTable -> ( -> EmployeeName varchar(20), -> JoiningDate date, -> Salary int -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('David', '2019-11-02', 400); Query OK, 1 row affected (0.52 sec) mysql> insert into DemoTable values('Robert', '2018-11-25', 100); Query OK, 1 row affected (0.39 sec) mysql> insert into DemoTable values('Bob', '2019-12-14', 600); Query OK, 1 row affected (0.25 sec) ...
Read MoreAdd records from corresponding duplicate values in another column with MySQL
For this, you can use the aggregate function SUM() along with the GROUP BY clause. Let us first create a table −mysql> create table DemoTable -> ( -> Name varchar(20), -> Value int -> ); Query OK, 0 rows affected (2.08 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris', 50); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('David', 90); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Chris', 60); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('Bob', 100); Query ...
Read MoreRatio_less () function in C++
Given is the task to show the working of ratio_less () function in C++.The function ratio_less() checks if the value of ratio1 is less than ratio2. It returns a Boolean constant “value” which returns true if ratio1 is less than ratio2 else returns false.ExampleInput: 1/3 and 3/9 Output: 1/3 is less than 3/9. Input: 1/4 and 1/8 Output: 1/4 is not less than 1/8.SyntaxTemplate ratio_lessParametersThis function accepts two template parameters one is ratio1 and another one is ratio2 which are to be compared.ExplanationIn this function, if the value of ratio1 is less than the value of ratio2 then this ...
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