代码在循环内不起作用，但在循环外起作用

Question

我有一段代码显示出一些奇怪的行为。当代码被排除在 for 循环之外时，它按预期工作，但是一旦我将它放在 for 循环中，它就会一次又一次地重复相同的值。

  const double *north = cp->getValues();
  angle1 = atan2(north[1], north[2]);
  bearing = (angle1 - 1.5708) / M_PI * 180.0;
  std::cout<<"Bearing inside : "<<bearing<<std::endl;
  if (bearing < 0.0)
    bearing = bearing + 360.0;
  t = abs(bearing - turn);

这部分代码应该在每次对象旋转时更新 *north。每当我将这段代码放在循环之外时，就会发生这种情况。但是一旦代码保存在 for 循环中，如下所示，*north 的值保持不变。

    for(int i=0;i<100;i++)
    {
      double t_modifier = (180.0 - abs(t)) / 180.0;
      double threshold = 2.0;
      double Speedleft = 1.0;
      double Speedright = 1.0;
      int identifier;
      if(int(t)<0){
        Speedleft = -1;
      }
      else if(int(t)>0){
        Speedright = -1;
      }
      leftSpeed = threshold * Speedleft;
      rightSpeed = threshold * Speedright;
      {
        wheels[0]->setVelocity(leftSpeed);
        wheels[1]->setVelocity(rightSpeed);
        wheels[2]->setVelocity(leftSpeed);
        wheels[3]->setVelocity(rightSpeed);
      }
      
      const double *north = cp->getValues();
      angle1 = atan2(north[1], north[2]);
      bearing = (angle1 - 1.5708) / M_PI * 180.0;
      std::cout<<"Bearing inside : "<<bearing<<std::endl;
      if (bearing < 0.0)
        bearing = bearing + 360.0;
      t = abs(bearing - turn);
    }

Answer 1

你应该在循环中调用step方法：
https://cyberbotics.com/doc/reference/robot#wb_robot_step

step方法的深入解释：
https://cyberbotics.com/doc/guide/controller-programming#the-step-and-wb_robot_step-functions

代码在循环内不起作用，但在循环外起作用

Code doesn't work inside a loop but works outside the loop

loops

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