C++通過升序

Question

我試圖排序第一矢量 向量升推回第一向量和分選矢量[0]爲x1的點，那麼它的長度總是改變

vector<int> v1; 
v1.push_back(l[0]); 
vector<int>::iterator Iter = v1.begin(); 
for (Iter = v1.begin(); Iter != v1.end(); Iter++){ 
sort(v1.begin(), v1.end()); 
cout << *Iter << endl; 

它沒有任何錯誤，但不能按順序排序。我該如何解決它？

編輯--------------------------------------------- -------------------------------

void thresh_callback(int, void*) 
{ 

    /// Load source image and convert it to gray 
    src = imread(img_file, 1); 

    Mat threshold_output; 
    Mat threshold_output1; 
    Mat dst; 
    vector<vector<Point> > contours; 

    /// Detect edges using Threshold 
    Canny(src_hist, threshold_output, thresh, thresh * 3, 3, false); 
    Sharpen(threshold_output, threshold_output1); 


    cvtColor(threshold_output1, dst, CV_GRAY2BGR); 

    vector<Vec4i> lines; 
    HoughLinesP(threshold_output1, lines, 1, CV_PI/180, thresh1, min_line, max_gap); 

    int erosion_size = 1; 
    Mat element = getStructuringElement(MORPH_ERODE, 
     Size(2 * erosion_size + 1, 2 * erosion_size + 1), 
     Point(erosion_size, erosion_size)); 

    /// Apply the erosion operation 
    dilate(dst, dst, element); 

    imshow("Source", dst); 

    for (size_t i = 0; i < lines.size(); i++) 
    { 
     Vec4i l = lines[i]; 
     Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255)); 
     int dx = l[2] - l[0]; 
     int dy = l[3] - l[1]; 

     double rad = atan2(dx, dy); 
     double degree = (rad * 180)/M_PI; 

     if (degree >= 180) degree -= 180; 
     if (degree < 15 || degree > 165) { 
      line(src, Point(l[0], l[1]), Point(l[2], l[3]), Scalar(0, 0, 255), 1, 8); 
      //printf("%lf\n", degree); 
      //printf("%d, %d, %d, %d, %d\n", l[0], l[1], l[2], l[3], i); 

      vector<int> v1; 
      v1.push_back(l[0]); 
      vector<int>::iterator Iter = v1.begin(); 
      sort(v1.begin(), v1.end()); 
      for (Iter = v1.begin(); Iter != v1.end(); Iter++){ 
       cout << *Iter << endl; 
      } 
     } 
     imshow("source", src); 
    } 

} 

我用houghline找出點x1，x2， y1，y2 並得到每x1和排序升序

Answer 1

不確定這是你的問題，但是......你在for循環內定義v1。

for (size_t i = 0; i < lines.size(); i++) 
{ 
    // ... 

     vector<int> v1; 
     v1.push_back(l[0]); 
     vector<int>::iterator Iter = v1.begin(); 
     sort(v1.begin(), v1.end()); 
     for (Iter = v1.begin(); Iter != v1.end(); Iter++){ 
      cout << *Iter << endl; 
     } 
    // ... 
} 

那麼，你每次迭代，創建載體，插入一個單一的元素，排序向量（具有單個元素），打印單個值和破壞載體。

建議：在for循環之外定義v1。

---編輯---

正如指出的aichao，排序和打印部分大概是更好的外部for循環;像

vector<int> v1; 

for (size_t i = 0; i < lines.size(); i++) 
{ 
    // ... 

     v1.push_back(l[0]); 

    // ... 
} 

sort(v1.begin(), v1.end()); 

for (vector<int>::const_iterator CIter = v1.cbegin(); CIter != v1.cend(); CIter++) { 
    cout << *CIter << endl; 
} 

如果你可以編譯C++ 11或C++ 14，最後for可以簡單

for (auto const & i : v1) 
    cout << i << endl; 

P.S：對不起，我的英語不好。