[英]error with “expression must have a constant value”
我是 C++ 的新手。 我正在嘗試制作一個可以找到平均值、最大值、最小值和中值的程序。 我不確定我在代碼中做錯了什么,我收到double scores[n];
:
#include <iostream>
#include<iomanip>
#include "ArrayFunction.h"
using namespace std;
int main()
{
int n;
double scores[n];
cout << "Enter the number of your scores: ";
cin >> n;
// creat the input array
// read the elements into the array
for (int i = 0; i < n; i++)
{
cout << "Enter " << n << " scores: ";
cin >> scores[i];
}
// call the functions and display for the result
cout << "Average of Score is: " << calcAverage(scores, n) << endl;
cout << "Min : " << calcMin(scores, n) << endl;
cout << "Max : " << calcMax(scores, n) << endl;
cout << "Median : " << calcMedian(scores, n) << endl;
}
ArrayFunction.h
template <typename T>
long double calcAverage(T* arr, int size) {
long double total = 0;
//Compute the sum
for (int i = 0; i < size; i++)
total = total + *(arr + i);
//return the average
return total / size;
}
template <typename T>
T calcMax(T* arr, int size) {
//Initilize the max
T max = arr[0];
//Find the max out of the remaining elements
for (int i = 1; i < size; i++)
if (max < arr[i])
max = arr[i];
//Return the max element
return max;
}
template <typename T>
T calcMin(T* arr, int size) {
//Initilize the min element
T min = arr[0];
//Find the min out of the remaining elements
for (int i = 1; i < size; i++)
if (min > arr[i])
min = arr[i];
//Return the max element
return min;
}
template <typename T>
long double calcMedian(T* arr, int size) {
T temp;
//Create a temp array
T arr2[size];
//Copy the array
for (int i = 0;i < size;i++)
arr2[i] = arr[i];
//Sort the array
for (int i = 0;i < size - 1;i++) {
for (int j = i + 1;j < size;j++) {
if (arr2[i] > arr2[j]) {
temp = arr2[i];
arr2[i] = arr[j];
arr2[j] = temp;
}
}
}
//IF the size of array is even then we add the mid and min+1 elements
//compute the average
if (size % 2 == 0) {
return (arr2[size / 2] + arr2[size / 2 + 1]) / 2.0;
}
//If the size is odd the we return the middle element
return arr2[size / 2];
}
我嘗試輸入一個數字並得到一個不同的錯誤:
數組類型 T 大小不可分配
我已經搜索並且 C++ 不支持可變長度 arrays,我應該使用std::vector
代替。
您可以在編譯時聲明一個已知大小的數組! 所以大小必須是恆定的!
int values[10];
int values2[] ={1,2,3};
constexpr int size = 10;
int values3[size];
const int size2 =5;
int values4[size2];
以上所有示例都是在編譯時使用 const size 定義的!
對於運行時初始化,您可以使用指針!
int* values = new int[1];
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