C++ Programming Code Examples
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Get the difference between two sets
/* Get the difference between two sets */
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
void print(int elem) {
cout << elem << " ";
}
int main(int argc, char** argv) {
vector<int> setOne, setTwo, setThree;
setOne.push_back(1);
setOne.push_back(2);
setOne.push_back(3);
setTwo.push_back(2);
setTwo.push_back(3);
setTwo.push_back(4);
// set algorithms work on sorted ranges
sort(setOne.begin(), setOne.end());
sort(setTwo.begin(), setTwo.end());
vector<int>::iterator newEnd = set_difference(setOne.begin(), setOne.end(), setTwo.begin(),setTwo.end(), setThree.begin());
cout << "The difference between set one and set two is: ";
for_each(setThree.begin(), newEnd, &print);
cout << endl;
return (0);
}
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.
Difference of two sorted ranges. Constructs a sorted range beginning in the location pointed by result with the set difference of the sorted range [first1,last1) with respect to the sorted range [first2,last2). The difference of two sets is formed by the elements that are present in the first set, but not in the second one. The elements copied by the function come always from the first range, in the same order. For containers supporting multiple occurrences of a value, the difference includes as many occurrences of a given value as in the first range, minus the amount of matching elements in the second, preserving order. Notice that this is a directional operation - for a symmetrical equivalent, see set_symmetric_difference.
Sort elements in range. Sorts the elements in the range [first,last) into ascending order. The elements are compared using operator< for the first version, and comp for the second. Equivalent elements are not guaranteed to keep their original relative order (see stable_sort). C++ Algorithm sort() function is used to sort the elements in the range [first, last) into ascending order. The elements are compared using operator < for the first version, and comp for the second version. std::sort() is a built-in function in C++'s Standard Template Library. The function takes in a beginning iterator, an ending iterator, and (by default) sorts the iterable in ascending order. The function can also be used for custom sorting by passing in a comparator function that returns a boolean.
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Apply function to range. Applies function fn to each of the elements in the range [first,last). C++ algorithm::for_each function is used to apply the specified function fn to each element in the range [first, last). for_each loop applies a function to the range of elements of a collection. In other words each element from the collection will be passed to the function as a parameter and function will be executed the number of times elements present in a collection. This loop is defined in a algorithm header so have to include this header in your program to use for_each
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.
#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.
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Consider a situation, when we have two persons with the same name, jhon, in the same class. Whenever we need to differentiate them definitely we would have to use some additional information along with their name, like either the area, if they live in different area or their mother's or father's name, etc. Same situation can arise in your C++ applications. For example, you might be writing some code that has a function called xyz() and there is another library available which is also having same function xyz(). Now the compiler has no way of knowing which version of xyz() function you are referring to within your code.
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.
C++ program sample to implement Sieve of Eratosthenes. Program initializes an integer array with all the "elements initialized" to 0. Then The Algorithm follows where the each
