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Remove(delete) all elements in the vector
/* Remove(delete) all elements in the vector */
#include <iostream>
using std::cout;
using std::endl;
#include <vector> // vector class-template definition
#include <algorithm> // copy algorithm
#include <iterator> // ostream_iterator iterator
#include <stdexcept> // out_of_range exception
int main()
{
int array[ 6 ] = { 1, 2, 3, 4, 5, 6 };
std::vector< int > integers( array, array + 6 );
std::ostream_iterator< int > output( cout, " " );
integers.push_back( 2 );
integers.push_back( 3 );
integers.push_back( 4 );
cout << "Vector integers contains: ";
std::copy( integers.begin(), integers.end(), output );
// erase remaining elements
integers.erase( integers.begin(), integers.end() );
cout << "\nAfter erasing all elements, vector integers "
<< ( integers.empty() ? "is" : "is not" ) << " empty";
return 0;
}
/*
Vector integers contains: 1 2 3 4 5 6 2 3 4
After erasing all elements, vector integers is empty
*/
In C++, vectors are used to store elements of similar data types. However, unlike arrays, the size of a vector can grow dynamically. That is, we can change the size of the vector during the execution of a program as per our requirements. Vectors are part of the C++ Standard Template Library. To use vectors, we need to include the vector header file in our program. The vector class provides various methods to perform different operations on vectors. Add Elements to a Vector: To add a single element into a vector, we use the push_back() function. It inserts an element into the end of the vector. Access Elements of a Vector: In C++, we use the index number to access the vector elements. Here, we use the at() function to access the element from the specified index.
Return iterator to beginning. Returns an iterator pointing to the first element in the vector. Notice that, unlike member vector::front, which returns a reference to the first element, this function returns a random access iterator pointing to it. If the container is empty, the returned iterator value shall not be dereferenced. The C++ function std::vector::begin() returns a random access iterator pointing to the first element of the vector. This function does not accept any parameter.
This class defines the type of objects thrown as exceptions to report an out-of-range error. Defines a type of object to be thrown as exception. It reports errors that are consequence of attempt to access elements out of defined range. It may be thrown by the member functions of std::bitset and std::basic_string, by std::stoi and std::stod families of functions, and by the bounds-checked member access functions (e.g. std::vector::at and std::map::at). It is a standard exception that can be thrown by programs. Some components of the standard library, such as vector, deque, string and bitset also throw exceptions of this type to signal arguments out of range.
copy() function is used to copy items from one iterator to another iterator with a specific range. We can define the start and end position of the source and it will copy all items in this rage to a different destination. To use copy() function, we need to include <bits/stdc+.h> or header file. It copies all the elements pointed by first and last. first element is included in the output but last is not. output is the start position of the final result iterator. It returns one iterator to the end of the destination range where elements have been copied. Function returns an iterator to the end of the destination range where elements have been copied.
Ostream iterators are output iterators that write sequentially to an output stream (such as cout). They are constructed from a basic_ostream object, to which they become associated, so that whenever an assignment operator (=) is used on the ostream_iterator (dereferenced or not) it inserts a new element into the stream. Optionally, a delimiter can be specified on construction. This delimiter is written to the stream after each element is inserted.
Test whether vector is empty. Returns whether the vector is empty (i.e. whether its size is 0). This function does not modify the container in any way. To clear the content of a vector, see vector::clear. Vectors are same as dynamic arrays with the ability to resize itself automatically when an element is inserted or deleted, with their storage being handled automatically by the container. vector::empty() is a library function of "vector" header, it is used to check whether a given vector is an empty vector or not, it returns a true if the vector size is 0, otherwise it returns false.
Erase elements. Removes from the vector either a single element (position) or a range of elements ([first,last)). This effectively reduces the container size by the number of elements removed, which are destroyed. Because vectors use an array as their underlying storage, erasing elements in positions other than the vector end causes the container to relocate all the elements after the segment erased to their new positions. This is generally an inefficient operation compared to the one performed for the same operation by other kinds of sequence containers (such as list or forward_list).
#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.
Iterators are just like pointers used to access the container elements. Iterators are one of the four pillars of the Standard Template Library or STL in C++. An iterator is used to point to the memory address of the STL container classes. For better understanding, you can relate them with a pointer, to some extent. Iterators act as a bridge that connects algorithms to STL containers and allows the modifications of the data present inside the container. They allow you to iterate over the container, access and assign the values, and run different operators over them, to get the desired result. • Iterators are used to traverse from one element to another element, a process is known as iterating through the container. • The main advantage of an iterator is to provide a common interface for all the containers type. • Iterators make the algorithm independent of the type of the container used.
An array is defined as the collection of similar type of data items stored at contiguous memory locations. Arrays are the derived data type in C++ programming language which can store the primitive type of data such as int, char, double, float, etc. It also has the capability to store the collection of derived data types, such as pointers, structure, etc. The array is the simplest data structure where each data element can be randomly accessed by using its index number. C++ array is beneficial if you have to store similar elements. For example, if we want to store the marks of a student in 6 subjects, then we don't need to define different variables for the marks in the different subject. Instead of that, we can define an array which can store the marks in each subject at the contiguous memory locations.
Add element at the end. Adds a new element at the end of the vector, after its current last element. The content of val is copied (or moved) to the new element. This effectively increases the container size by one, which causes an automatic reallocation of the allocated storage space if -and only if- the new vector size surpasses the current vector capacity. push_back() function is used to push elements into a vector from the back. The new value is inserted into the vector at the end, after the current last element and the container size is increased by 1. This function does not return any value.
A program shall contain a global function named main, which is the designated start of the program in hosted environment. main() function is the entry point of any C++ program. It is the point at which execution of program is started. When a C++ program is executed, the execution control goes directly to the main() function. Every C++ program have a main() function.
Return iterator to end. Returns an iterator referring to the past-the-end element in the vector container. The past-the-end element is the theoretical element that would follow the last element in the vector. It does not point to any element, and thus shall not be dereferenced. Because the ranges used by functions of the standard library do not include the element pointed by their closing iterator, this function is often used in combination with vector::begin to specify a range including all the elements in the container. If the container is empty, this function returns the same as vector::begin. This function does not accept any parameter.
Put character. Inserts character c into the stream. Internally, the function accesses the output sequence by first constructing a sentry object. Then (if good), it inserts c into its associated stream buffer object as if calling its member function sputc, and finally destroys the sentry object before returning. Function returns the ostream object (*this).
First 'Compare the Element' at the beginning with another array element sequentially. And swap values if the element at the beginning is Larger than the other element. This value will
This program asks user to enter 'two integers' and displays all Armstrong numbers between the "given interval". If you don't know how to check whether a number is 'Armstrong' or not
This is a C++ Program to implement Graham Scan algorithm. 'Graham's scan' is a method of computing the convex hull of a finite set of points in the plane with time complexity O(n
