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我做了一个表达式求值器，但我只包括：加法和减法和乘法和除法和括号解析器，我想添加指数“^”，之后，三角函数：正弦，余弦和正切但我不'吨知道从哪里开始......这是我现在所做的：添加指数
public static string RemoveBrackets(string text)
{
while (text.Contains('(') && text.Contains(')'))
{
int openIndex = 0;
int closeIndex = 0;
for(int i = 0; i < text.Length; ++i)
{
if(text[i] == '(')
{
openIndex = i;
}
if(text[i] == ')')
{
closeIndex = i;
text = text.Remove(openIndex, closeIndex - openIndex + 1).Insert(openIndex, ResolveBrackets(openIndex, closeIndex, text));
break;
}
}
}
for(int i = 1; i < text.Length; ++i)
{
if(text[i] == '-' && (text[i - 1] == '*' || text[i - 1] == '/'))
{
for(int j = i - 1; j >= 0; --j)
{
if(text[j] == '+')
{
StringBuilder text1 = new StringBuilder(text);
text1[j] = '-';
text = text1.ToString();
text = text.Remove(i, 1);
break;
}
else if(text[j] == '-')
{
StringBuilder text1 = new StringBuilder(text);
text1[j] = '+';
text = text1.ToString();
text = text.Remove(i, 1);
break;
}
}
}
}
for (int i = 0; i < text.Length; ++i)
{
if (text[i] == '-' && (text[i - 1] == '-' || text[i - 1] == '+'))
{
if(text[i - 1] == '-')
{
StringBuilder text1 = new StringBuilder(text);
text1[i] = '+';
text = text1.ToString();
text = text.Remove(i - 1, 1);
}
else
{
StringBuilder text1 = new StringBuilder(text);
text1[i] = '-';
text = text1.ToString();
text = text.Remove(i - 1, 1);
}
}
else if (text[i] == '+' && (text[i - 1] == '-' || text[i - 1] == '+'))
{
if (text[i - 1] == '-')
{
StringBuilder text1 = new StringBuilder(text);
text1[i] = '-';
text = text1.ToString();
text = text.Remove(i - 1, 1);
}
else
{
StringBuilder text1 = new StringBuilder(text);
text1[i] = '+';
text = text1.ToString();
text = text.Remove(i - 1, 1);
}
}
}
if (text[0] == '-')
{
text = '0' + text;
}
return Calculate(text);
}
public static string ResolveBrackets(int openindex, int closeindex, string text)
{
string BracketAnswer = evaluate(text.Substring(openindex + 1, closeindex - openindex - 1));
return BracketAnswer;
}
public static double DivideAndMultiply(string text)
{
string[] expr = text.Split('*');
List<string> textList = new List<string>();
for (int i = 0; i < expr.Length; ++i)
{
textList.Add(expr[i]);
if (i != expr.Length - 1)
{
textList.Add("*");
}
}
for (int i = 0; i < textList.Count; ++i)
{
if (textList[i].Contains('/') && textList[i].Length > 1)
{
string[] textPart = textList[i].Split('/');
textList.RemoveAt(i);
for (int j = textPart.Length - 1; j >= 0; --j)
{
textList.Insert(i, textPart[j]);
if (j != 0)
{
textList.Insert(i, "/");
}
}
}
}
double total;
if (textList[0].Contains('*') || textList[0].Contains('/'))
{
total = textList[0] == "" ? 0 : DivideAndMultiply(textList[0]);
}
else
{
total = Convert.ToDouble(textList[0]);
}
/// 7:30 min tutorial
for (int i = 2; i < textList.Count; i += 2)
{
if (textList[i - 1] == "/")
{
total /= Convert.ToDouble(textList[i]);
}
else if (textList[i - 1] == "*")
{
total *= Convert.ToDouble(textList[i]);
}
}
return total;
}
public static double AddAndSubstract(string text)
{
string[] expr = text.Split('-');
List<string> textList = new List<string>();
for(int i = 0; i < expr.Length; ++i)
{
textList.Add(expr[i]);
if(i != expr.Length - 1)
{
textList.Add("-");
}
}
for(int i = 0; i < textList.Count; ++i)
{
if (textList[i].Contains('+') && textList[i].Length > 1)
{
string[] textPart = textList[i].Split('+');
textList.RemoveAt(i);
for (int j = textPart.Length - 1; j >= 0; --j)
{
textList.Insert(i, textPart[j]);
if (j != 0)
{
textList.Insert(i, "+");
}
}
}
}
//double total = Add(expr[0]);
double total = expr[0] == "" ? 0 : DivideAndMultiply(textList[0]);
for (int i = 2; i < textList.Count; i += 2)
{
if(textList[i - 1] == "-")
{
total -= DivideAndMultiply(textList[i]);
}
else if(textList[i - 1] == "+")
{
total += DivideAndMultiply(textList[i]);
}
}
return total;
}
我应该读什么的建议？
你应该问你最喜欢的搜索引擎关于'递归下降解析器'。 –
滚动one..scroll两个...无聊滚动 - 太多的代码。 – Reniuz
@Reniuz将注意力集中在AddandSubstract和DivideAndMultiply函数上...... –