C++ <list> clear Function
clearis used for in listClear all elementsThe function is the simplest and most efficient way to clear a container.
clearIt is a member function of the container class, used to delete all elements in the linked list, making the list empty.
After calling, the linked list'ssize()will become 0.
Word Definitions： clearIt means "clear," i.e., delete all elements.
Basic syntax and parameters
clearIt is a member function of the container class, and calling it requires no parameters.
Syntax format
void clear();
Function description
- Return Value：
void(no return value). - Effect: Delete all elements in the linked list,
size()becomes 0.
Example
Example 1: Clear the linked list
Example
#include <iostream>
#include <list>
int main() {
std::list<int> numbers = {1, 2, 3, 4, 5};
std::cout << "Before clearing - size: " << numbers.size() << std::endl;
numbers.clear();
std::cout << "After clearing - size: " << numbers.size() << std::endl;
return 0;
}
#include <list>
int main() {
std::list<int> numbers = {1, 2, 3, 4, 5};
std::cout << "Before clearing - size: " << numbers.size() << std::endl;
numbers.clear();
std::cout << "After clearing - size: " << numbers.size() << std::endl;
return 0;
}
Expected output:
清空前 - size: 5 清空后 - size: 0
Example 2: Reuse after clearing
Example
#include <iostream>
#include <list>
int main() {
std::list<int> data;
data.push_back(1);
data.push_back(2);
std::cout << "After the first addition: " << data.size() << std::endl;
data.clear();
data.push_back(10);
data.push_back(20);
data.push_back(30);
std::cout << "After clearing and re-adding: ";
for(int n : data) std::cout << n << " ";
std::cout << std::endl;
return 0;
}
#include <list>
int main() {
std::list<int> data;
data.push_back(1);
data.push_back(2);
std::cout << "After the first addition: " << data.size() << std::endl;
data.clear();
data.push_back(10);
data.push_back(20);
data.push_back(30);
std::cout << "After clearing and re-adding: ";
for(int n : data) std::cout << n << " ";
std::cout << std::endl;
return 0;
}
Expected output:
第一次添加后: 2 清空后重新添加: 10 20 30
other extensions