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C++ Tour Part III
Shared Pointer A shared pointer is a smart pointer that allows for distributed ownership of data. Each time it is assigned, a reference count is incremented, indicating one more owner of the data. When the pointer goes out of scope or an owner calls reset , the reference count is decremented. When the reference count goes to 0, the data pointed to is deallocated. Use make_shared : auto person = std :: make_shared < Person > ( ) ; if ( person ) { cout << "Person's address is " << person -> address ; } C++17 allows use of shared pointers to point to dynamically allocated arrays. However, make_shared cannot be used. Below is an example: shared_ptr < Person [ ] > persons ( new Person [ 10 ] ) ; persons [ 0 ] . _name = "Jack Sparrow" ; persons [ 0 ] . _address = "Caribbean" ; cout << "Address of first person " << persons [ 0 ] . address << endl ; A better solutio...
C++ strings and string_view
C-style strings C style strings should be avoided except when interfacing with C libraries. C string library functions provide no bounds checking and memory allocation support. They are represented as an array of characters. Last character of the string is the null character \0 , so that code that uses the string knows where it ends. The space needed for a string is always one more than the number of readable characters. String Literals Strings written with quotes around them are string literals. They are stored in a read-only part of memory. Because they are stored in readonly sections, attempting to modify string literals is undefined behavior . Example: char * str = "world" ; str [ 0 ] = 'y' ; //undefined behavior If the code respected the standard and assigned the string literal to const char* , the compiler will catch attempts to modify string literals: const char * str = "world" ; str [ 0 ] = 'k' ; //compiler will f...
STL Part I
Introduction to STL Containers expose the iterator interface and the Algorithms work on the iterators . std::vector Example of iterating through a vector is below. Iterator behaves like an enhanced pointer. # include <iostream> using namespace std ; int main ( ) { vector < int > nums ; nums . push_back ( 3 ) ; nums . push_back ( 1 ) ; nums . push_back ( 2 ) ; vector < int > :: iterator first = nums . begin ( ) ; vector < int > :: iterator onePastLast = nums . end ( ) ; for ( vector < int > :: iterator i = first ; i != onePastLast ; i ++ ) { cout << "Next Element is " << * i << endl ; } //sorting a vector sort ( first , onePastLast ) ; //after sorting 1,2,3 } Types of containers Sequence containers(array and linked list): vector, deque, list, forward list, and array Associative containers (binary tree) : set, multiset, map...
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