C++ <list> insert function
insertis used in list forInserts an element at a specified positionfunctions, and is the most flexible operation of linked lists.
insertIs a member function of the container class, used to insert one or more elements at a specified position in the linked list.
In the list,insertHas a time complexity of O(1), because only pointers need to be adjusted.
Word Definitions： insertMeans "insert," i.e., adding an element at a specified position.
Basic syntax and parameters
insertIs a member function of the container class, requiring the insertion position and element to be specified.
Syntax format
iterator insert(iterator pos, const T& value); iterator insert(iterator pos, T&& value); void insert(iterator pos, size_type count, const T& value); template<class InputIt> void insert(iterator pos, InputIt first, InputIt last);
Parameter description
- Parameter：
pos- Iterator of the insertion position - Parameter：
value- The value of the element to insert
Function description
- Return Value: Returns an iterator pointing to the first inserted element.
- Effect: Inserts an element at the specified position, and subsequent elements are shifted backward in order.
Example
Example 1: Basic usage - inserting a single element
Example
#include <iostream>
#include <list>
int main() {
std::list<int> numbers = {1, 2, 3, 4, 5};
std::cout << "original list: ";
for(int n : numbers) std::cout << n << " ";
std::endl;
// Insert 100 at the second position (iterator)
auto it = std::next(numbers.begin(), 1);
numbers.insert(it, 100);
std::cout << "After inserting 100: ";
for(int n : numbers) std::cout << n << " ";
std::cout << std::endl;
return 0;
}
#include <list>
int main() {
std::list<int> numbers = {1, 2, 3, 4, 5};
std::cout << "original list: ";
for(int n : numbers) std::cout << n << " ";
std::endl;
// Insert 100 at the second position (iterator)
auto it = std::next(numbers.begin(), 1);
numbers.insert(it, 100);
std::cout << "After inserting 100: ";
for(int n : numbers) std::cout << n << " ";
std::cout << std::endl;
return 0;
}
Expected running result:
原始 list: 1 2 3 4 5 插入 100 后: 1 100 2 3 4 5
Example 2: Inserting multiple elements
Example
#include <iostream>
#include <list>
int main() {
std::list<int> numbers = {1, 5};
std::cout << "Original: ";
for(int n : numbers) std::cout << n << " ";
std::cout << std::endl;
// Insert 3 zeros in the middle
auto it = numbers.begin();
std::advance(it, 1);
numbers.insert(it, 3, 0);
std::cout << After inserting 3 zeros:;
for(int n : numbers) std::cout << n << " ";
std::cout << std::endl;
return 0;
}
#include <list>
int main() {
std::list<int> numbers = {1, 5};
std::cout << "Original: ";
for(int n : numbers) std::cout << n << " ";
std::cout << std::endl;
// Insert 3 zeros in the middle
auto it = numbers.begin();
std::advance(it, 1);
numbers.insert(it, 3, 0);
std::cout << After inserting 3 zeros:;
for(int n : numbers) std::cout << n << " ";
std::cout << std::endl;
return 0;
}
Expected running result:
原始: 1 5 插入 3 个 0 后: 1 0 0 0 5
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