什么是元组？ 元组是一个可以容纳许多元素的对象。元素可以是不同的数据类型。元组的元素按访问顺序初始化为参数。
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元组运算 :-
1.得到 ：-get（）用于访问和修改元组值，它接受索引和元组名称作为参数来访问特定的元组元素。
2.生成元组（） ：-make_tuple（）用于为tuple赋值。传递的值应与元组中声明的值保持顺序。
// C++ code to demonstrate tuple, get() and make_pair() #include<iostream> #include<tuple> // for tuple using namespace std; int main() { // Declaring tuple tuple < char , int , float > geek; // Assigning values to tuple using make_tuple() geek = make_tuple( 'a' , 10, 15.5); // Printing initial tuple values using get() cout << "The initial values of tuple are : " ; cout << get<0>(geek) << " " << get<1>(geek); cout << " " << get<2>(geek) << endl; // Use of get() to change values of tuple get<0>(geek) = 'b' ; get<2>(geek) = 20.5; // Printing modified tuple values cout << "The modified values of tuple are : " ; cout << get<0>(geek) << " " << get<1>(geek); cout << " " << get<2>(geek) << endl; return 0; } |
输出：
The initial values of tuple are : a 10 15.5 The modified values of tuple are : b 10 20.5
在上面的代码中，get（）修改元组的第1个和第3个值。
3.元组大小 ：-它返回元组中存在的元素数。
//C++ code to demonstrate tuple_size #include<iostream> #include<tuple> // for tuple_size and tuple using namespace std; int main() { // Initializing tuple tuple < char , int , float > geek(20, 'g' ,17.5); // Use of size to find tuple_size of tuple cout << "The size of tuple is : " ; cout << tuple_size< decltype (geek)>::value << endl; return 0; } |
输出：
The size of tuple is : 3
4.互换 ：-swap（），交换两个不同元组的元素。
//C++ code to demonstrate swap() #include<iostream> #include<tuple> // for swap() and tuple using namespace std; int main() { // Initializing 1st tuple tuple < int , char , float > tup1(20, 'g' ,17.5); // Initializing 2nd tuple tuple < int , char , float > tup2(10, 'f' ,15.5); // Printing 1st and 2nd tuple before swapping cout << "The first tuple elements before swapping are : " ; cout << get<0>(tup1) << " " << get<1>(tup1) << " " << get<2>(tup1) << endl; cout << "The second tuple elements before swapping are : " ; cout << get<0>(tup2) << " " << get<1>(tup2) << " " << get<2>(tup2) << endl; // Swapping tup1 values with tup2 tup1.swap(tup2); // Printing 1st and 2nd tuple after swapping cout << "The first tuple elements after swapping are : " ; cout << get<0>(tup1) << " " << get<1>(tup1) << " " << get<2>(tup1) << endl; cout << "The second tuple elements after swapping are : " ; cout << get<0>(tup2) << " " << get<1>(tup2) << " " << get<2>(tup2) << endl; return 0; } |
输出：
The first tuple elements before swapping are : 20 g 17.5 The second tuple elements before swapping are : 10 f 15.5 The first tuple elements after swapping are : 10 f 15.5 The second tuple elements after swapping are : 20 g 17.5
5.领带 ：-tie（）的工作是将元组值解压成单独的变量。tie（）有两种变体，有“ignore”和没有“ignore”，而“ignore”会忽略一个特定的元组元素，并阻止它被解包。
// C++ code to demonstrate working of tie() #include<iostream> #include<tuple> // for tie() and tuple using namespace std; int main() { // Initializing variables for unpacking int i_val; char ch_val; float f_val; // Initializing tuple tuple < int , char , float > tup1(20, 'g' ,17.5); // Use of tie() without ignore tie(i_val,ch_val,f_val) = tup1; // Displaying unpacked tuple elements // without ignore cout << "The unpacked tuple values (without ignore) are : " ; cout << i_val << " " << ch_val << " " << f_val; cout << endl; // Use of tie() with ignore // ignores char value tie(i_val,ignore,f_val) = tup1; // Displaying unpacked tuple elements // with ignore cout << "The unpacked tuple values (with ignore) are : " ; cout << i_val << " " << f_val; cout << endl; return 0; } |
输出：
The unpacked tuple values (without ignore) are : 20 g 17.5 The unpacked tuple values (with ignore) are : 20 17.5
6.tuple_cat（） ：-此函数连接两个元组并返回一个新元组。
// C++ code to demonstrate working of tuple_cat() #include<iostream> #include<tuple> // for tuple_cat() and tuple using namespace std; int main() { // Initializing 1st tuple tuple < int , char , float > tup1(20, 'g' ,17.5); // Initializing 2nd tuple tuple < int , char , float > tup2(30, 'f' ,10.5); // Concatenating 2 tuples to return a new tuple auto tup3 = tuple_cat(tup1,tup2); // Displaying new tuple elements cout << "The new tuple elements in order are : " ; cout << get<0>(tup3) << " " << get<1>(tup3) << " " ; cout << get<2>(tup3) << " " << get<3>(tup3) << " " ; cout << get<4>(tup3) << " " << get<5>(tup3) << endl; return 0; } |
输出：
The new tuple elements in order are : 20 g 17.5 30 f 10.5
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