C++ Programming Code Examples
C++ > Code Snippets Code Examples
Demonstrating the STL vector front and erase operations.
/* Demonstrating the STL vector front and erase operations. */
#include <iostream>
#include <vector>
#include <string>
using namespace std;
int main()
{
string s("abcdefghij");
vector<char> vector1(s.begin(), s.end());
cout << "Popping characters off the front produces: ";
while (vector1.size() > 0) {
cout << vector1.front();
vector1.erase(vector1.begin());
}
cout << endl;
return 0;
}
/*
Popping characters off the front produces: abcdefghij
*/
Return size. Returns the number of elements in the vector. This is the number of actual objects held in the vector, which is not necessarily equal to its storage capacity. vector::size() is a library function of "vector" header, it is used to get the size of a vector, it returns the total number of elements in the vector. The dynamic array can be created by using a vector in C++. One or more elements can be inserted into or removed from the vector at the run time that increases or decreases the size of the vector. The size or length of the vector can be counted using any loop or the built-in function named size(). 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.
Return iterator to end. Returns an iterator pointing to the past-the-end character of the string. The past-the-end character is a theoretical character that would follow the last character in the string. It 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 string::begin to specify a range including all the characters in the string. If the object is an empty string, this function returns the same as string::begin.
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).
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.
Return iterator to beginning. Returns an iterator pointing to the first character of the string. This function gives a reference to the first element. The C++ string::begin function returns the iterator pointing to the first character of the string. Note that, Unlike the string::front function, which returns a direct reference to the first character, it returns the iterator pointing to the same character of the string. This function does not return any value.
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.
In while loop, condition is evaluated first and if it returns true then the statements inside while loop execute, this happens repeatedly until the condition returns false. When condition returns false, the control comes out of loop and jumps to the next statement in the program after while loop. The important point to note when using while loop is that we need to use increment or decrement statement inside while loop so that the loop variable gets changed on each iteration, and at some point condition returns false. This way we can end the execution of while loop otherwise the loop would execute indefinitely. A while loop that never stops is said to be the infinite while loop, when we give the condition in such a way so that it never returns false, then the loops becomes infinite and repeats itself indefinitely.
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.
Access first element. Returns a reference to the first element in the vector. The C++ function std::vector::front() returns a reference to the first element of the vector. Unlike member vector::begin, which returns an iterator to this same element, this function returns a direct reference. Calling this function on an empty container causes undefined behavior. This function does not accept any parameter. Function returns a reference to the first element in the vector container.
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.
Program display the minimum heap method of arranging elements. "Minimum Heap" is a method of "Arranging Elements" in a Binary search tree where value of the parent node is
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 First Fit Decreasing for one dimensional objects and M bins. This is bin packing algorithm for first fit technique. Bubble Sort descending order
A B+ tree is an n-ary tree with a variable but often large number of "children per node". A B+ tree consists of a root, internal nodes and leaves. The root may be either a leaf or node
