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本文演示了一些可用于查询和操作数组类型(甚至是多维数组)的内置函数。在我们需要信息或操作我们用不同维度启动的数组的情况下,这些函数非常有用。这些函数在头文件 中定义。一些功能包括:
// 演示is_array()和is_same()工作的C++代码
#include<type_traits>
#include<iostream>
#include<array>
#include<string>
using namespace std;
int main()
{
// 使用is_array检查哪个是数组
cout << "Is Integer an array? : " << is_array<int>::value << endl;
cout << "Is Array an array? : " << is_array<int[10]>::value << endl;
cout << "Is 2D Array an array? : "
<< is_array<int[10][10]>::value << endl;
cout << "Is String an array? : " << is_array<string>::value << endl;
cout << "Is Character Array an array? : "
<< is_array<char[10]>::value << endl;
cout << "Is Array class type an array? : "
<< is_array<array<int,3>>::value << endl;
cout << endl;
// 使用is_same()检查相同类型
cout << "Is 2D array same as 1D array? : " <<
is_same<int[10],int[10][10]>::value << endl;
cout << "Is Character array same as Integer array? : "
<< is_same<int[10],char[10]>::value << endl;
cout << "Is 1D array same as 1D array (Different sizes) ? : "
<< is_same<int[10],int[20]>::value << endl;
cout << "Is 1D array same as 1D array? (Same sizes): "
<< is_same<int[10],int[10]>::value << endl;
return 0;
}
Is Integer an array? : 0
Is Array an array? : 1
Is 2D Array an array? : 1
Is String an array? : 0
Is Character Array an array? : 1
Is Array class type an array? : 0
Is 2D array same as 1D array? : 0
Is Character array same as Integer array? : 0
Is 1D array same as 1D array (Different sizes) ? : 0
Is 1D array same as 1D array? (Same sizes): 1
// 演示rank()工作的C++代码
#include<type_traits> // 用于数组查询函数
#include<iostream>
using namespace std;
int main()
{
// 检查不同类型的等级
cout << "The rank of integer is : " << rank<int>::value << endl;
cout << "The rank of 1D integer array is : "
<< rank<int[10]>::value << endl;
cout << "The rank of 2D integer array is : "
<< rank<int[20][10]>::value << endl;
cout << "The rank of 3D integer array is : "
<< rank<int[20][10][40]>::value << endl;
cout << "The rank of 1D character array is : "
<< rank<char[10]>::value << endl;
cout << endl;
}
输出:
The rank of integer is : 0
The rank of 1D integer array is : 1
The rank of 2D integer array is : 2
The rank of 3D integer array is : 3
The rank of 1D character array is : 1
// C++代码演示extent()、remove_extentt()和remove_all_extents()的工作
#include<type_traits> // 用于数组查询函数
#include<iostream>
using namespace std;
int main()
{
// 检查不同类型的范围(使用范围)
cout << "The extent of 1st dimension of 3D integer array is : " ;
cout << extent<int[20][10][40],0>::value << endl;
cout << "The extent of 2nd dimension of 3D integer array is : " ;
cout << extent<int[20][10][40],1>::value << endl;
cout << "The extent of 3rd dimension of 3D integer array is : " ;
cout << extent<int[20][10][40],2>::value << endl;
cout << "The extent of 4th dimension of 3D integer array is : " ;
cout << extent<int[20][10][40],3>::value << endl;
cout << endl;
// 正在删除类型的范围
cout << "The rank after removing 1 extent is : " ;
cout << rank<remove_extent<int[20][10][30]>::type>::value << endl;
//删除左侧的第一个维度
cout << "The extent of 1st after removing 1 extent is : " ;
cout << extent<remove_extent<int[20][10][30]>::type>::value << endl;
cout << endl;
// 删除类型的所有范围
cout << "The rank after removing all extents is : " ;
cout << rank<remove_all_extents<int[20][10][30]>::type>::value << endl;
// 删除所有范围
cout << "The extent of 1st after removing all extents is : " ;
cout << extent<remove_all_extents<int[20][10][30]>::type>::value << endl;
cout << endl;
}
输出:
The extent of 1st dimension of 3D integer array is : 20
The extent of 2nd dimension of 3D integer array is : 10
The extent of 3rd dimension of 3D integer array is : 40
The extent of 4th dimension of 3D integer array is : 0
The rank after removing 1 extent is : 2
The extent of 1st after removing 1 extent is : 10
The rank after removing all extents is : 0
The extent of 1st after removing all extents is : 0
如果大家发现什么不正确的地方,或者你想分享有关上述数组类型操作的更多内容,可以在下面评论。