algorithm 算法
1 generate
- 功能:作用于容器,以给定函数对象所生成的值赋值范围
[first, last)
中的每个元素
- 语法:
template< class ForwardIt, class Generator >
void generate( ForwardIt first, ForwardIt last, Generator g );
#include <algorithm>
#include <iostream>
#include <vector>
int f()
{
static int i;
return ++i;
}
int main()
{
std::vector<int> v(5);
auto print = [&] {
for (std::cout << "v: "; auto iv: v)
std::cout << iv << " ";
std::cout << "\n";
};
std::generate(v.begin(), v.end(), f);
print();
// 以来自 lambda 函数的值 0,1,2,3,4 初始化
// 等价于 std::iota(v.begin(), v.end(), 0);
std::generate(v.begin(), v.end(), [n = 0] () mutable { return n++; });
print();
}
v: 1 2 3 4 5
v: 0 1 2 3 4
template<class ForwardIt, class Generator>
constexpr // Since C++20
void generate(ForwardIt first, ForwardIt last, Generator g)
{
while (first != last) {
*first++ = g();
}
}