如何在 C++ 中打印出复数 Valarray 的最高元素?
我已尝试使用此代码,但它返回错误消息
#include <iostream> // std::cout
#include <valarray>
#include <complex>// std::valarray
typedef std::complex<double> Complex;
typedef std::valarray <Complex > CArray;
int main ()
{
CArray y[5]={{1, 2},{3, 4},{2,0},{7,0},{9,0}};
std::cout << "The max is " << y.max() << '\n';
return 0;
}
输出:
main.cpp: In function 'int main()':
main.cpp:15:35: error: request for member 'max' in 'y', which is of non-class type 'CArray [5] {aka std::valarray<std::complex<double> > [5]}'
std::cout << "The max is " << y.max() << '\n';
^
我做错了什么?
第二版代码我修改了一些代码,现在我想获取与我的 Valarray 的最高元素相对应的所有索引,在我的情况下,所有索引对应于元素 {9,0}
注意:“最高元素”是指具有最高实部的元素
新代码:
#include <iostream>
#include <valarray>
#include <complex>
#include <algorithm>
#include <numeric>
typedef std::complex<double> Complex;
typedef std::valarray <Complex > CArray;
int main ()
{
CArray y={{1, 2},{3, 4},{2,0},{9,0},{7,0},{9,0}};
auto max_val = std::accumulate (std::begin(y), std::end(y), *std::begin(y),
[](const Complex& a ,const Complex& b)
{
auto abs_a = abs(a);
auto abs_b = abs(b);
//if(abs_a == abs_b)
// return std::max(arg(a), arg(b));
return std::max(abs_a, abs_b);
}
);
for (std::size_t i =std::begin(y) ; i != std::end(y) ; i++) {
std::cout << "The max is found on index ["<< i <<"]" << max_val<< '\n';
}
return 0;
}
我收到以下错误:输出:
main.cpp: In function 'int main()':
main.cpp:22:35: error: invalid conversion from 'std::complex<double>*' to 'std::size_t {aka long unsigned int}' [-fpermissive]
for (std::size_t i =std::begin(y) ; i != std::end(y) ; i++) {
^
main.cpp:22:54: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
for (std::size_t i =std::begin(y) ; i != std::end(y) ; i++) {
^