Do-While 循环,但 while 语句的值在 Do 语句内
Posted
技术标签:
【中文标题】Do-While 循环,但 while 语句的值在 Do 语句内【英文标题】:Do-While Loops but the values for the while statement is inside the Do Statement 【发布时间】:2020-05-07 09:55:02 【问题描述】:我正在尝试通过编写一个程序来学习 C#,该程序可以找到系统达到平衡的两个值。我尝试了 Do-While 循环,但我无法建立 while 语句,因为 while 语句的值在 Do-statement 内。它只是说“变量在当前上下文中不存在”。我希望我说得通。
更新:完整代码发布在下面。我尝试了 while (true) 语句并添加了 if-break 语句。我真的不知道这是否是 if-break 语句的工作方式。循环不断地循环下去。我尝试打印值,但从第一个循环开始,它已经满足条件。
下面是我的代码:
using System;
using System.Linq;
public class BoltCoord
public double x1;
public double y1;
public class Program
public static void Main()
Console.Write("Number of Rows: ");
int nrow = int.Parse(Console.ReadLine());
Console.Write("Spacing of Rows: ");
double srow = double.Parse(Console.ReadLine());
Console.Write("Number of Columns: ");
int ncol = int.Parse(Console.ReadLine());
Console.Write("Spacing of Columns: ");
double scol = double.Parse(Console.ReadLine());
Console.Write("Eccentricity from CG: ");
double ecc = double.Parse(Console.ReadLine());
Console.Write("Rotation: ");
double rot = double.Parse(Console.ReadLine());
int totalbolts = nrow * ncol;
var boltgroupCG = BoltCG(nrow, ncol, srow, scol); // bolt group cg from first bolt
double[] xvaluesofbolts = new double[totalbolts]; //x-values of each bolt where first bolt is (0,0)
for (int ctr = 0; ctr < totalbolts; ctr++)
xvaluesofbolts[ctr] = (ctr % ncol) * srow;
double[] yvaluesofbolts = new double[totalbolts]; //y-values of each bolt where first bolt is (0,0)
for (int ctr = 1; ctr < totalbolts; ctr++)
yvaluesofbolts[ctr] = (ctr / ncol) * srow;
double[] FxOfBolts = new double[totalbolts];
double[] FyOfBolts = new double[totalbolts];
double[] MomOfBolts = new double[totalbolts];
double[] XTransOfBolts = new double[totalbolts]; // Translated X
double[] YTransOfBolts = new double[totalbolts]; // Translated Y
double[] XLi = new double[totalbolts]; // Translated X
double[] YLi = new double[totalbolts]; // Translated Y
double[] BoltDist = new double[totalbolts]; // from IC
double[] DeformBolts = new double[totalbolts];
double[] ReactionForce = new double[totalbolts];
double[] ReactionForceX = new double[totalbolts];
double[] ReactionForceY = new double[totalbolts];
double[] MomentBolt = new double[totalbolts];
var IC = new BoltCoord(); // from CG
double Px;
double Py;
double sumRx;
double sumRy;
double ctrX;
double ctrY;
do
for (ctrX = 0; ctrX < 50; ctrX = ctrX + 0.1)
for (ctrY = 0; ctrY < 50; ctrY = ctrY + 0.1)
for (int El = 0; El < totalbolts; El++)
XTransOfBolts[El] = xvaluesofbolts[El] - boltgroupCG.x1;
YTransOfBolts[El] = yvaluesofbolts[El] - boltgroupCG.y1;
XLi[El] = XTransOfBolts[El] + ctrX;
YLi[El] = YTransOfBolts[El] + ctrY;
BoltDist[El] = Math.Sqrt(Math.Pow(XLi[El], 2) + Math.Pow(YLi[El], 2));
double MaxDist = BoltDist.Max();
// int MaxIndex = Array.IndexOf(BoltDist, MaxDist);
double delta = 0.34;
double Rult = 74;
DeformBolts[El] = delta * BoltDist[El] / MaxDist;
ReactionForce[El] = Rult * Math.Pow((1 - Math.Exp(-10 * DeformBolts[El])), 0.55);
ReactionForceX[El] = ReactionForce[El] * YLi[El] / BoltDist[El];
ReactionForceY[El] = ReactionForce[El] * XLi[El] / BoltDist[El];
MomentBolt[El] = ReactionForce[El] * BoltDist[El];
sumRx = ReactionForceX.Sum();
sumRy = ReactionForceY.Sum();
double sumMoment = MomentBolt.Sum();
double sumReax = ReactionForce.Sum();
double ro = (ecc + ctrX) * Math.Cos(Math.PI * rot / 180) + ctrY * Math.Sin(Math.PI * rot / 180);
Px = sumMoment / ro;
Py = Px * Math.Cos(Math.PI * rot / 180);
Console.WriteLine(Px + " " + sumRx + " " + Py + " " + sumRy); // tried printing the values to see if loop happens.
// Px minus sumRx and Py minus sumRy are always less than 1000 but
// loop still continues?
if ((Px - sumRx <= 1000) && (Py - sumRy <= 1000))
break;
while (true); //((Px != sumRx) || (Py != sumRy));
public static BoltCoord BoltCG(int nrow, int ncol, double srow, double scol)
var BoltCGCoord = new BoltCoord
x1 = (ncol - 1) * scol * 0.5,
y1 = (nrow - 1) * srow * 0.5
;
return BoltCGCoord;
【问题讨论】:
500 / 0.001 * 500 / 0.001 * totalbolts == 2.5e11 * totalbolts
机器人(至少 250
十亿)。你真的想要那么多吗?
可能很明显,但是 PX 和 PY 是否在循环开始之前定义并可用?
【参考方案1】:
我把你的代码放到 dotnetfiddle.net 中,将 while 语句更改为时出现的错误
while((Px != sumRx) || (Py != sumRy))
是Use of unassigned local variable 'Px'
。为了不出现此错误,您需要在开始循环之前为 Px
sumRx
Py
和 sumRy
分配一个值。在循环上方,您可以将初始化更改为
double Px = 0;
double Py = 0;
double sumRx = 0;
double sumRy = 0;
double ctrX = 0;
double ctrY = 0;
此外,您的 break 语句不起作用,因为 break 语句适用于您当前的循环块,这是您最内层的 for 循环,因此您要跳出最内层的 for 循环,而不是跳出 while 循环。
【讨论】:
【参考方案2】:如果你替换
while ((Px != sumRx) || (Py != sumRy))
与
while (true)
代码可以编译吗?
如果不是,请确保在 do-while 循环开始之前声明了变量 Px、Py、sumRx、sumRy。
double Px, Py, sumRx, sumRy;
do
...
【讨论】:
嗨。感谢您的回复。我已经更新了我的帖子并发布了上面的完整代码。【参考方案3】:为什么循环继续循环的一般答案是你的 for 循环会检查每个条件,这意味着它会循环 nrow * ncol 次数,即使它确实在第一次找到答案. 这是假设在您运行的代码中没有注释掉这一行。 (而 true 将永远永远循环)。
while (true); //((Px != sumRx) || (Py != sumRy));
其中的 break 语句退出了最里面的 for 循环。如果您想保持早期突破,您还需要为所有循环编写突破逻辑。总的来说,这很丑陋,这是一个很好的例子,说明为什么嵌套循环和 if 语句会很快变得丑陋。 :)
希望对您有所帮助。
【讨论】:
以上是关于Do-While 循环,但 while 语句的值在 Do 语句内的主要内容,如果未能解决你的问题,请参考以下文章