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Programming Articles
Page 2338 of 2547
How to replace backward "" slash from a string
In Python it does give the desired result>>> var = "aaa\bbb\ccc and ddd\eee" >>> var.split('') ['aaa', 'bbb', 'ccc and ddd', 'eee']
Read MoreWhere can I find the current C or C++ standard documents?
You can find the current C standard documents on ANSI web store. https://webstore.ansi.org/RecordDetail.aspx?sku=INCITS%2FISO%2FIEC+9899-2012You can find the current C++ standard documents on the ISO C++ website for buying − https://www.iso.org/standard/68564.htmlThe working draft of the ISO C++ standard is also available on https://isocpp.org/std/the-standard
Read MoreWhen should static_cast, dynamic_cast, const_cast and reinterpret_cast be used in C++?
const_castcan be used to remove or add const to a variable. This can be useful if it is necessary to add/remove constness from a variable.static_castThis is used for the normal/ordinary type conversion. This is also the cast responsible for implicit type coersion and can also be called explicitly. You should use it in cases like converting float to int, char to int, etc.dynamic_castThis cast is used for handling polymorphism. You only need to use it when you're casting to a derived class. This is exclusively to be used in inheritence when you cast from base class to derived class.reinterpret_castThis is ...
Read MoreWhat is the copy-and-swap idiom in C++?
The assignment consists of 2 steps, tearing an object's old state and building a new state for it. The destructor is used for the first step and a copy constructor does the second step. Implementing both of these is straightforward. But when overloading the assignment operator, it can become quite difficult to implement. The copy and swap idiom is a solution for the same.This idiom uses the copy-constructor to build a local copy of the data. It then swaps the old data with the new data using the swap function. The temporary copy is then destructed using the destructor. We ...
Read MoreWhy is it faster to process a sorted array than an unsorted array in C++?
In C++, it is faster to process a sorted array than an unsorted array because of branch prediction. In computer architecture, a branch prediction determines whether a conditional branch (jump) in the instruction flow of a program is likely to be taken or not.Let’s take an example −if(arr[i] > 50) { Do some operation B } else { Do some operation A }If we run this code for 100 elements in unsorted and sorted order below things will be happened −For sorted array −1, 2, 3, 4, 5, …… 50, 51………100 A, A, A, A, A A, B ...
Read MoreWhat is The Rule of Three with reference to C++?
The Rule of three is a rule of thumb when using C++. This is kind of a good practice rule that says that If your class needs any ofa copy constructor, an assignment operator, or a destructor, defined explicitly, then it is likely to need all three of them.Why is this? Its because, if your class requires any of the above, it is managing dynamically allocated resources and would likely be needing the other to successfully achieve that. For example, if you require an assignment operator, you would be creating copies of objects currently being copied by reference, hence allocating ...
Read MoreWhat are undefined reference/unresolved external symbol errors in C++?
As the name suggests, a symbol you declared was not defined by you. This may occur due to many cases. Let's have a look at three of them −You forgot to define the declared name. For example, you declared a function in a file and used it somewhere. But you did not provide its definition. Code −#include void foo(); int main() { foo(); // Declared but not defined }You defined it but did not use the qualified name. Say you created a class with a method and defined that method but forgot using scope resolution to link that function ...
Read MoreWhy we can't use arrow operator in gets and puts?
You can't read user input in an un-initialized pointer. Instead, have a variable of the struct data type and assign its address to pointer before accessing its inner elements by → operatorexample#include struct example{ char name[20]; }; main(){ struct example *ptr; struct example e; puts("enter name"); gets(e.name); ptr=&e; puts(ptr->name); }OutputTypical result of above codeenter name Disha You entered Disha
Read MoreWhy we should use whole string in Java regular expression
In Java regex matches() matches the input string against the whole string as it add a ^ and $ at the end of the input string.so it will not match the substring. So for matching substring, you should use find().Exampleimport java.util.regex.*; class PatternMatchingExample { public static void main(String args[]) { String content = "aabbcc"; String string = "aa"; Pattern p = Pattern.compile(string); Matcher m = p.matcher(content); System.out.println(" 'aa' Match:"+ m.matches()); System.out.println(" 'aa' Match:"+ m.find()); } }Output'aa' Match:false 'aa' Match:true
Read MoreHow to extract a group from a Java String that contains a Regex pattern
How to extract a group from a Java String that contains a Regex patternimport java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexTest { public static void main(String[] args) { Pattern pattern = Pattern.compile("fun"); Matcher matcher = pattern.matcher("Java is fun"); // using Matcher find(), group(), start() and end() methods while (matcher.find()) { System.out.println("Found the text "" + matcher.group() + "" starting at " + matcher.start() + " index and ending at index ...
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