Question

我正在使用C ++计算NACA 4位翼型坐标。在这段代码中，我使用了armadillo库的linspace函数将x分成线性间隔的点。当我使用for循环计算每个x值的#include<iostream> #include<armadillo> #include<vector> using namespace std; using namespace arma; int main() { float a[3]; float c; int gp = 100; cout << "Please Enter NACA 4 digits" << endl; cout << "Please Enter 1st digit" << endl; cin >> a[0] ; cout << "Please Enter 2nd digit" << endl; cin >> a[1] ; cout << "Please Enter last 2 digits" << endl; cin >> a[2] ; cout << "Please Enter Chord Length" << endl; cin >> c; float m=(a[0]*c)/100; float p=(a[1]*c)/10; float t=(a[2]*c)/100; cout << m << endl; cout << p << endl; cout << t << endl; vec x = linspace<vec>(0, c, gp); float yc; for(int i=0;i<gp;++i) { if (x(i) = 0 && x(i) <= p){ yc(i) = (m/(p*p))*((2*p*(x(i)))-(x(i)*x(i))); } if (x(i) > p && x(i) <= c) { yc(i) =(m/((1-p)*(1-p)))*((1-(2*p))+(2*p*x(i))-(x(i)*x(i))); } } cout<< yc <<endl; return 0; }值时，我得到错误“yc”不能用作函数。谢谢你的帮助。

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Answer 1

yc是一个浮动。

编译器将symbol( )视为函数调用。这就是错误的含义。

也许创建一个yc数组

float yc[gp];

并使用

yc[i] = ....

如突出显示 - yc[gp]可能不起作用，所以

float * yc = new float[gp];

在main()

结束时

delete []yc;

Answer 2

以下是如何使用std::vector进行此类任务的示例。

vector<float> v(size);声明使用size类型为float的值填充向量，这些值均设置为0.0，这是float的标准值：

#include <iostream>
#include <vector>

using namespace std;

// demonstrates how a vector is used as a better variadic array:
void vector_usage(int size){

    // initializing a vector with size 0 values
    std::vector<float> v(size);

    // fill in some (not very meaningful) values
    for(int i=0; i<size; ++i) {
        if ((4 <= i) && (i < 8))
            v[i] = 15.0/i;
    }

    // inspect the result on console:
    for (auto e: v) {
        cout << e << " ";
    }
    cout << endl;

    // hopefully having learned something ;)

}

int main() {
    vector_usage(12);
    return 0;
}

^{See the live demo on ideone.com ...}

“'yc'不能用作C ++中的函数”错误

2 个答案: