【代码笔记】【c#】计算后缀表达式

分手后的思念是犯贱 2022-11-28 13:18 109阅读 0赞

/// <summary>
    		/// 计算后缀表达式
    		/// </summary>
    		/// <param name="expression">后缀表达式</param>
    		/// <returns></returns>
    		public static double CalSu(String expression) 
    		{ 
    			string[] units = expression.Trim().Split(' ');
    			Stack arguments = new Stack();
    
    			foreach (string unit in units)
    			{ 
    				if (isNumberic(unit))
    				{ 
    					arguments.Push(double.Parse(unit));
    				}
    				else
    				{ 
    					double value = (double)arguments.Pop();
    
    					switch (unit)
    					{ 
    						case "+":
    							arguments.Push((double)arguments.Pop() + value);
    							break;
    
    						case "-":
    							arguments.Push((double)arguments.Pop() - value);
    							break;
    
    						case "*":
    							arguments.Push((double)arguments.Pop() * value);
    							break;
    
    						case "/":
    							arguments.Push((double)arguments.Pop() / value);
    							break;
    
    						case "sin":
    							arguments.Push(Math.Sin(value));
    							break;
    
    						case "cos":
    							arguments.Push(Math.Cos(value));
    							break;
    
    						case "ln":
    							arguments.Push(Math.Log(value));
    							break;
    
    						case "exp":
    							arguments.Push(Math.Exp(value));
    							break;
    
    						case "sqrt":
    							arguments.Push(Math.Sqrt(value));
    							break;
    
    						default:
    							throw new ArgumentException("未知的符号" + unit);
    					}
    				}
    			}
    
    			if (arguments.Count != 1)
    			{ 
    				throw new ArgumentException("表达式不合法");
    			}
    
    			return (double)arguments.Pop();
    
    		}