vector 可以动态的变大。
array 是固定大小的，就是一个普通的数组，可以使用迭代器。
构造函数
#include <iostream>
#include <array>
std::array<int, 3> global; //initialized as: {0,0,0}
int main()
{
std::array<int, 3> first; //uninitialized
std::array<int, 3> second = { 10, 20 }; //initialized as: {10,20,0}
std::array<int, 3> third = { 1, 2, 3 }; //initialized as: {1,2,3}
std::array<int, 3> fourth = third;
for (auto x : fourth)
std::cout << ' ' << x;
std::cout << '\n';
return 0;
}
at()
返回一个引用。
#include <iostream>
#include <array>
int main()
{
std::array<int, 10> myarray;
for (int i = 0; i < 10; i++)
myarray.at(i) = i + 1;
std::cout << "myarray contains:";
for (int i = 0; i < 10; i++)
std::cout << ' ' << myarray.at(i);
std::cout << '\n';
return 0;
}
front(), back()
front() 返回第一个元素的引用。
back() 返回最后一个元素的引用。
#include <iostream>
#include <array>
int main()
{
std::array<int, 3> myarray = { 2, 16, 77 };
std::cout << "front is: " << myarray.front() << std::endl;
std::cout << "back is: " << myarray.back() << std::endl;
myarray.front() = 100;
myarray.back() = 99;
for (int & x : myarray)
std::cout << ' ' << x;
std::cout << '\n';
return 0;
}
begin(), end()
#include <iostream>
#include <array>
int main()
{
std::array<int, 5> myarray = { 2, 16, 77, 34, 50 };
for (auto it = myarray.begin(); it != myarray.end(); ++it)
{
std::cout << ' ' << *it;
}
std::cout << '\n';
return 0;
}
size(), max_size()
size() 和 max_size() 好像是一样的。
#include <iostream>
#include <array>
int main()
{
std::array<int, 10> myints;
std::cout << "size of myints: " << myints.size() << std::endl; //10
std::cout << "max_size of myints: " << myints.max_size() << std::endl; //10
std::cout << "sizeof(myints): " << sizeof(myints) << std::endl; //40
return 0;
}
data()
返回指向第一个元素的指针。
#include <iostream>
#include <cstring>
#include <array>
int main()
{
const char * cstr = "Test string";
std::array<char, 12> charray;
std::memcpy(charray.data(), cstr, 12);
std::cout << charray.data() << '\n';
return 0;
}
operator []
#include <iostream>
#include <array>
int main()
{
std::array<int, 10> myarray;
unsigned int i;
for (i = 0; i < 10; i++)
myarray[i] = i;
for (i = 0; i < 10; i++)
std::cout << ' ' << myarray[i];
std::cout << '\n';
return 0;
}
