C++ Programming Code Examples
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Merge and splice lists.
/* Merge and splice lists. */
#include <iostream>
#include <list>
using namespace std;
int main()
{
list<char> listObject1, listObject2, listObject3;
int i;
for(i = 0; i <10; i+=2)
listObject1.push_back(i + 'A');
for(i =1; i <11; i+=2)
listObject2.push_back(i + 'A');
cout << "Contents of listObject1:\n";
list<char>::iterator p = listObject1.begin();
while(p != listObject1.end()) {
cout << *p << " ";
p++;
}
cout << "\n\n";
cout << "Contents of listObject2:\n";
p = listObject2.begin();
while(p != listObject2.end()) {
cout << *p << " ";
p++;
}
cout << "\n\n";
listObject1.merge(listObject2); // now, merge the two lists
if(listObject2.empty())
cout << "listObject2 is now empty\n";
cout << "Contents of listObject1 after merge:\n";
p = listObject1.begin();
while(p != listObject1.end()) {
cout << *p << " ";
p++;
}
cout << "\n\n";
char str[] = "-splicing-";
for(i = 0; str[i]; i++)
listObject3.push_back(str[i]);
cout << "Contents of listObject3:\n";
p = listObject3.begin();
while(p != listObject3.end()) {
cout << *p << " ";
p++;
}
cout << "\n\n";
p = listObject1.begin();
while(p != listObject1.end()) {
if(*p == 'F') listObject1.splice(p, listObject3);
p++;
}
cout << "Contents of listObject1 after splice:\n";
p = listObject1.begin();
while(p != listObject1.end()) {
cout << *p << " ";
p++;
}
return 0;
}
List is a popularly used sequence container. Container is an object that holds data of same type. List container is implemented as doubly linked-list, hence it provides bidirectional sequential access to it's data. List doesn't provide fast random access, it only supports sequential access in both directions. List allows insertion and deletion operation anywhere within a sequence in constant time. Elements of list can be scattered in different chunks of memory. Container stores necessary information to allow sequential access to it's data. Lists can shrink or expand as needed from both ends at run time. The storage requirement is fulfilled automatically by internal allocator. Zero sized lists are also valid. In that case list.begin() and list.end() points to same location. But behavior of calling front() or back() is undefined. To define the std::list, we have to import the <list> header file.
Return iterator to beginning. Returns an iterator pointing to the first element in the list container. Notice that, unlike member list::front, which returns a reference to the first element, this function returns a bidirectional iterator pointing to it. If the container is empty, the returned iterator value shall not be dereferenced. begin() function is used to return an iterator pointing to the first element of the list container. It is different from the front() function because the front function returns a reference to the first element of the container but begin() function returns a bidirectional iterator to the first element of the container. This function does not accept any parameter. Function returns an iterator to the beginning of the sequence container.
Return iterator to end. Returns an iterator referring to the past-the-end element in the list container. The past-the-end element is the theoretical element that would follow the last element in the list container. 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 list::begin to specify a range including all the elements in the container. If the container is empty, this function returns the same as list::begin. This function does not accept any parameter.
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Test whether container is empty. Returns whether the list container is empty (i.e. whether its size is 0). The C++ list::empty function is used to check whether the list is empty or not. It returns true if the size of the list is zero, else returns false. This function does not modify the container in any way. To clear the content of a list container, see list::clear. No parameter is passed to the function. Function returns true if the container size is 0, false otherwise.
Merge sorted lists. Merges x into the list by transferring all of its elements at their respective ordered positions into the container (both containers shall already be ordered). This effectively removes all the elements in x (which becomes empty), and inserts them into their ordered position within container (which expands in size by the number of elements transferred). The operation is performed without constructing nor destroying any element: they are transferred, no matter whether x is an lvalue or an rvalue, or whether the value_type supports move-construction or not. The template versions with two parameters (2), have the same behavior, but take a specific predicate (comp) to perform the comparison operation between elements. This comparison shall produce a strict weak ordering of the elements (i.e., a consistent transitive comparison, without considering its reflexiveness).
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