OpenMP的截斷浮子

Question

我從CSV文件轉換成float陣列讀取數據（1維/載體）和施加快速排序它：

int main() 
{ 

float floatArr[2000]; 

ReadRandomData(floatArr, "D:\RandomData.csv"); 

//#pragma omp parallel 
{ 
    QuickSort(floatArr, 0,2000); 
} 

for(int i=0; i<2000; i++) 
{ 
    cout<<floatArr[i]<<endl; 
} 

_getch(); 

} 

和輸出的東西像這樣：

但一旦我取消了#pragma omp parallel部分，歐tput的是這樣的（其截斷我認爲）：

任何人都可以解釋我爲什麼會這樣使用OpenMP以及如何解決它？提前致謝！

UPDATE

這裏是快速排序部分：

void QuickSort(float* arr, int startIndex, int endIndex) 
{ 
    int pivot = arr[startIndex];     //pivot element is the leftmost element 
    int splitPoint; 

if(endIndex > startIndex)      //if they are equal, it means there is only one element and quicksort's job here is finished 
{ 
    splitPoint = Splitarr(arr, pivot, startIndex, endIndex); 
                //Splitarr() returns the position where pivot belongs to 
    arr[splitPoint] = pivot; 
    QuickSort(arr, startIndex, splitPoint-1); //Quick sort first half 
    QuickSort(arr, splitPoint+1, endIndex); //Quick sort second half 
} 

}

這裏是分裂碼：

int Splitarr(float* arr, int pivot, int startIndex, int endIndex) 
{ 
    int leftBoundary = startIndex; 
    int rightBoundary = endIndex; 

while(leftBoundary < rightBoundary)   //shuttle pivot until the boundaries meet 
{ 
    while(pivot < arr[rightBoundary]  //keep moving until a lesser element is found 
      && rightBoundary > leftBoundary)  //or until the leftBoundary is reached 
    { 
      rightBoundary--;      //move left 
    } 

      swap(arr[leftBoundary], arr[rightBoundary]); 


    while(pivot >= arr[leftBoundary]  //keep moving until a greater or equal element is found 
      && leftBoundary < rightBoundary)  //or until the rightBoundary is reached 
    { 
      leftBoundary++;      //move right 
    } 

      swap(arr[rightBoundary], arr[leftBoundary]); 

} 

return rightBoundary;        //leftBoundary is the split point because 
                //the above while loop exits only when 
                //leftBoundary and rightBoundary are equal 
} 

Answer 1

您的算法中有一件事我認爲是造成問題。

更改行：

int pivot = arr[startIndex]; 

到

float pivot = arr[startIndex]; 

轉換浮到INT截斷小數，如您正確設定。這可能會解決您的問題。