如何迭代收集和更改值

Question

我知道這是一個愚蠢的問題，因爲您不能在循環中修改循環集合，但我確實需要更改它。我知道我不能改變被引用的對象，但我不知道該怎麼做。

var orders = _orderService.GetOrders(o => !o.Deleted && 
              o.OrderStatus != OrderStatus.Cancelled && 
              o.OrderStatus != OrderStatus.Complete); 
foreach (var order in orders) 
{ 
    if (order.PaymentStatus == PaymentStatus.Paid) 
    { 
     if (order.ShippingStatus == ShippingStatus.ShippingNotRequired || order.ShippingStatus == ShippingStatus.Delivered) 
     {  
      var tempOrder = _orderService.GetOrderById(order.Id);     
      SetOrderStatus(tempOrder , OrderStatus.Complete, true); 
     } 
    } 
} 

我總是得到一個錯誤。

更新：我改變了這個

var orders = _orderService.GetOrders(o => !o.Deleted && 
         o.OrderStatus != OrderStatus.Cancelled && o.OrderStatus != OrderStatus.CompletE); 

      List<int> orderIndex = new List<int>(); 
      orders.ToList().ForEach(x => orderIndex.Add(x.Id)); 

      foreach(var index in orderIndex) 
      { 
       var order = _orderService.GetOrderById(index); 
       if (order.PaymentStatus == PaymentStatus.Paid) 
       { 
        if (order.ShippingStatus == ShippingStatus.ShippingNotRequired || order.ShippingStatus == ShippingStatus.Delivered) 
        { 

         SetOrderStatus(order, OrderStatus.Complete, true); 
        } 
       } 
      } 

Answer 1

使用的循環，而不是foreach循環

for(int i=0; i<orders.Count; i++) 
{ 
    if (orders[i].PaymentStatus == PaymentStatus.Paid) 
    { 
     if (orders[i].ShippingStatus == ShippingStatus.ShippingNotRequired || orders[i].ShippingStatus == ShippingStatus.Delivered) 
     {  
      var tempOrder = _orderService.GetOrderById(orders[i].Id);     
      SetOrderStatus(tempOrder , OrderStatus.Complete, true); 
     } 
    } 
} 

Answer 2

嘗試

int count = orders.Count; // the length of the collect : may need a different method for different collection types. 
for(int i = 0; i < count; i++) 
{ 
    var current = orders[i]; 
    // do stuff with current. 
}