std :: sort（）C ++不能工作，但它如此简单，原因:(一维数组

This should be really simple, I have found that the first argument is the array name, the second is the size of the array + array name. However, it doesnt seem to be sorting at all, in fact its not doing anything, well not writing anything on the console, am I doing somethin silly?

这应该很简单,我发现第一个参数是数组名,第二个是数组+数组名的大小。然而,它似乎根本就没有排序,实际上它没有做任何事情,也没有在控制台上写任何东西,我在做些什么傻事?

int main()
{
    readFromFile();
    system("pause");
    return 0;
}

void readFromFile()
{
    string line;
    int i = 0;
    int j;
    ifstream file("ACW2_data.txt");

if(file.is_open())
{
    getline(file, line);

    while (!file.eof())
    {
        file >> numbers[i];
        i++;
        int elements = sizeof(numbers) / sizeof(numbers[0]);
        **sort(numbers, numbers + elements);**
    }
    file.close();
}
else
{
    cout << "Cant open the file" << endl;
}

for(j = 0; j < i; j++)
{
    cout << numbers[j] << endl;
}

system("pause");
}

what do you guys think?

你们有什么感想?

4 个解决方案

#1

while (!file.eof())
{
    file >> numbers[i];
    i++;
    int elements = sizeof(numbers) / sizeof(numbers[0]);
    **sort(numbers, numbers + elements);**
}
file.close();

while (file >> numbers[i])
{
    ++i;
}
sort( numbers, numbers + i );
file.close();

std::vector<your_int_type> numbers;
your_int_type tmp;
while (file >> tmp)
{
    numbers.push_back(tmp);
}
std::sort( numbers.begin(), numbers.end() );
file.close();

#2

Edit: For the moment, I'm assuming numbers was an array of int. If not, well, I'll hope you can figure out what to do...

编辑:目前,我假设数字是一个int数组。如果没有,那么,我希望你能弄明白该做什么......

int main() { 
    std::ifstream file("ACW2_data.txt");

    std::vector<int> numbers;

    file.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

    std::copy(std::istream_iterator<int>(file),
              std::istream_iterator<int>(),
              std::back_inserter(numbers));

    std::sort(numbers.begin(), numbers.end());

    std::copy(numbers.begin(), numbers.end(), 
              std::ostream_iterator<int>(std::cout, "\n"));
    return 0;
}

#3

First, where is numbers defined, and what is its type?

首先,数字定义在哪里,它的类型是什么?

Second, the number of elements in numbers is i at every iteration of the while loop, so you do not need to calculate it.

其次,在while循环的每次迭代中,数字中的元素数量是i,因此您不需要计算它。

Third, why are you sorting numbers every time you insert a new element? Why not insert all the elements, and then sort once. After the while loop that is.

第三,为什么每次插入新元素时都要对数字进行排序?为什么不插入所有元素,然后排序一次。在while循环之后。

#4

My wild guess, since you are not showing the important detail of how numbers is declared, is that it is a pointer, and the sizeof trick is failing to calculate the allocated size. It is better to use a template based sizeof like:

我猜测,因为你没有显示如何声明数字的重要细节,它是一个指针,并且sizeof技巧无法计算分配的大小。最好使用基于模板的sizeof,如:

template <typename T, int N>
int array_size( T (&)[N] ) {
   return N;
}

or:

template <typename T, int N>
char (&array_size_impl( T(&)[N] ))[N];
#define ARRAY_SIZE( x ) sizeof( array_size_impl( x ) )

As those will trigger compile time errors if a pointer is used, instead of silently failing and yielding unexpected results as the sizeof(x)/sizeof(x[0]) trick.

因为如果使用指针,这些将触发编译时错误,而不是静默失败并产生意外的结果作为sizeof(x)/ sizeof(x [0])技巧。

#1

while (!file.eof())
{
    file >> numbers[i];
    i++;
    int elements = sizeof(numbers) / sizeof(numbers[0]);
    **sort(numbers, numbers + elements);**
}
file.close();

while (file >> numbers[i])
{
    ++i;
}
sort( numbers, numbers + i );
file.close();

std::vector<your_int_type> numbers;
your_int_type tmp;
while (file >> tmp)
{
    numbers.push_back(tmp);
}
std::sort( numbers.begin(), numbers.end() );
file.close();

#2