C++數組複製/移位

Question

我們有一個項目，要求我們編寫一個程序，允許用戶輸入一系列數字「將數字讀入數組中進行進一步處理，用戶信號通過輸入負數來完成（在計算中不使用負數），在讀完所有數字後，執行以下操作，總結＃輸入的數字，計算輸入的數字，找到輸入的最小/最大值，計算平均值，然後將它們輸出到屏幕上所以在這種工作，我做的樣子版本，所以

/* Reads data into array. 
paramater a = the array to fill 
paramater a_capacity = maximum size 
paramater a_size = filled with size of a after reading input. */ 

void read_data(double a[], int a_capacity, int& a_size) 
{ 
    a_size = 0; 

bool computation = true; 

while (computation) 
{ 
    double x; 
    cin >> x; 

    if (x < 0) 
     computation = false; 

    else if (a_size == a_capacity) 
    { 
     cout << "Extra data ignored\n"; 
     computation = false; 
    } 
    else 
    { 
     a[a_size] = x; 
     a_size++; 
    } 
} 
} 


/* computes the maximum value in array 
paramater a = the array 
Paramater a_size = the number of values in a */ 

double largest_value(const double a[], int a_size) 
{ 
if(a_size < 0) 
    return 0; 

double maximum = a[0]; 

for(int i = 1; i < a_size; i++) 
    if (a[i] > maximum) 
     maximum = a[i]; 
return maximum; 

} 


/* computes the minimum value in array */ 
double smallest_value(const double a[], int a_size) 
{ 
if(a_size < 0) 
    return 0; 

double minimum = a[0]; 

for(int i = 1; i < a_size; i++) 
    if (a[i] < minimum) 
     minimum = a[i]; 
return minimum; 
} 

//computes the sum of the numbers entered 
double sum_value(const double a [], int a_size) 
{ 
if (a_size < 0) 
    return 0; 

double sum = 0; 

for(int i = 0; i < a_size; i++) 
    sum = sum + a[i]; 
return sum; 
} 

//keeps running count of numbers entered 
double count_value(const double a[], int a_size) 
{ 
if (a_size < 0) 
    return 0; 

int count = 0; 
for(int i = 1; i <= a_size; i++) 
    count = i; 
return count; 

} 



int _tmain(int argc, _TCHAR* argv[]) 
{ 

const int INPUT_CAPACITY = 100; 
double user_input[INPUT_CAPACITY]; 
int input_size = 0; 
double average = 0; 

cout << "Enter numbers. Input negative to quit.:\n"; 

read_data(user_input, INPUT_CAPACITY, input_size); 

double max_output = largest_value(user_input, input_size); 
cout << "The maximum value entered was " << max_output << "\n"; 

double min_output = smallest_value(user_input, input_size); 
cout << "The lowest value entered was " << min_output << "\n"; 

double sum_output = sum_value(user_input, input_size); 
cout << "The sum of the value's entered is " << sum_output << "\n"; 

double count_output = count_value(user_input, input_size); 
cout << "You entered " << count_output << " numbers." << "\n"; 

cout << "The average of your numbers is " << sum_output/count_output << "\n"; 




string str; 

getline(cin,str); 
getline(cin,str); 


return 0; 
} 

這都很好，我有現在的問題是部分二，我們要「數組複製到另一個和N檔的數組元素「，我不知道從哪一個開始，我擡起頭來關於複製數組的一些資源，但我不確定如何在我已完成的當前代碼中實現它們，特別是當涉及到轉換時。如果任何人有任何想法，想法或資源，可以幫助我在正確的道路上，將不勝感激。我也應該指出，我是一個初學者（這是一個初學者課程），所以這項任務可能不是「最佳」的方式，但是如果有意義的話，我們可以將它們合併到一起。

Answer 1

for(int i = 0; i < n; ++i){ 
    int j = (i - k)%n; 
    b[i] = a[j]; 
} 

檢查它。我不知道 如果這個工程，你就能把提高

for(int i = 0; i < n; ++i) 
    b[i] = a[(i - k)%n];//here can be (i +/- k) it depends which direction u would shift 

Answer 2

如果你只想陣列複製到另一個陣列和轉移他們

例如：輸入= 1，2，3，4 ，5;輸出= 3，4，5，1，2

的麻煩的解決方案是

//no template or unsafe void* since you are a beginner 

int* copy_to(int *begin, int *end, int *result) 
{ 
    while(begin != end){ 
    *result = *begin; 
    ++result; ++begin; 
    } 

    return result; 
} 

int main() 
{ 
    int input[] = {1, 2, 3, 4, 5}; 
    size_t const size = sizeof(input)/sizeof(int); 
    size_t const begin = 2; 
    int output[size] = {0}; //0, 0, 0, 0, 0 

    int *result = copy_to(input + begin, input + size - begin, output); //3, 4, 5, 0, 0 
    copy_to(input, input + begin, result); //3, 4, 5, 1, 2 

    return 0; 
} 

如何可以在STL算法設定幫助我們？

的read_data保持你提供

#include <algorithm> //std::minmax_element, std::rotate_copy 
#include <iostream> 
#include <iterator> //for std::begin() 
#include <numeric> //for std::accumulate() 
#include <string> 
#include <vector> 

int main(int argc, char *argv[]) //don't use _tmain, they are unportable 
{ 

const int INPUT_CAPACITY = 100; 
double user_input[INPUT_CAPACITY]; 
int input_size = 0; 
double average = 0; 

cout << "Enter numbers. Input negative to quit.:\n"; 

read_data(user_input, INPUT_CAPACITY, input_size); 

auto const min_max = std::minmax_element (user_input, user_input + input_size); //only valid for c++11 

std::cout << "The maximum value entered was " << min_max.second << "\n"; 
std::cout << "The lowest value entered was " << min_max.first << "\n"; 

double sum_output = std::accumulate(user_input, user_input + input_size, 0); 
cout << "The sum of the value's entered is " << sum_output << "\n"; 

//I don't know the meaning of you count_value, why don't just output input_size? 
double count_output = count_value(user_input, input_size); 
cout << "You entered " << count_output << " numbers." << "\n"; 

cout << "The average of your numbers is " << sum_output/count_output << "\n"; 

int shift; 
std::cout<<"How many positions do you want to shift?"<<std::endl; 
std::cin>>shift; 
std::vector<int> shift_array(input_size); 
std::rotate_copy(user_input, user_input + shift, user_input + input_size, std::begin(shift_array)); 


//don't know what are they for? 
std::string str; 

std::getline(std::cin,str); 
std::getline(std::cin,str); 

return 0; 
} 

如果你的編譯器不支持C++ 11個功能尚未

的std :: minmax_element可以通過 的std :: min_element和std更換同一個： ：max_element 的std ::開始（）可以通過shift_array.begin（）

我不知道你是什麼類的教學風格，在我的愚見更換，初學者應該 啓動與C++提供的更高級別的組件，如向量，字符串，算法 等等。我假設你的老師正在教你這種方式，你可以使用 算法和容器與c + +（讓我們乞求你的課是沒有教你「上課」，並說「OOP是世界上最好的東西」）。

PS：你可以使用載體，如果你喜歡