最近因项目需求，做了一个简易的四则混合运算解析模块。例如计算表达式：34 * ((300+4) / 2) - ((300 - 4) % 2)注：运算符仅支持: + - * / % 五种类型
public interface IMixedCalculate
{
T Exec<T>(string expression);
} 接口实现类：
public class MixedCalculate : IMixedCalculate
{
Regex bracketRg = null;
/// <summary>
/// 乘 - 除 - % 运算
/// </summary>
Regex calcLevel1 = null;
/// <summary>
/// 加 - 减 运算
/// </summary>
Regex calcLevel2 = null;
const int max = 100;
public MixedCalculate()
{
bracketRg = new Regex(@"\((?<CalculateExp>[^\(\)]+)\)", RegexOptions.IgnoreCase);
calcLevel1 = new Regex(@"(?<Num1>[0-9\.]+)\s*(?<CalcChar>[\/\*\%])\s*(?<Num2>[0-9\.]+)", RegexOptions.IgnoreCase);
calcLevel2 = new Regex(@"(?<Num1>[0-9\.]+)\s*(?<CalcChar>[\+\-])\s*(?<Num2>[0-9\.]+)", RegexOptions.IgnoreCase);
}
T IMixedCalculate.Exec<T>(string expression)
{
T val = default(T);
if (string.IsNullOrEmpty(expression)) return val;
BracketCalculate(ref expression);
Level_Calculate(calcLevel1, ref expression);
Level_Calculate(calcLevel2, ref expression);
string s = expression.Trim();
object vObj = ConvertTo<T>(s); //这里是基本数据类型转换
if (null != vObj) val = (T)vObj;
return val;
}
object ConvertTo<T>(string vs)
{
Type type = typeof(T);
object vObj = null;
if (typeof(int) == type)
{
int n = 0;
int.TryParse(vs, out n);
vObj = n;
}
else if(typeof(float) == type)
{
float fNum = 0;
float.TryParse(vs, out fNum);
vObj = fNum;
}
else if (typeof(double) == type)
{
double dbNum = 0;
double.TryParse(vs, out dbNum);
vObj = dbNum;
}
return vObj;
}
void Level_Calculate(Regex rg, ref string expression)
{
string s = expression.Trim();
if (string.IsNullOrEmpty(s)) return;
int n = 0;
string Num1 = "";
string Num2 = "";
string CalcChar = "";
float n1 = 0;
float n2 = 0;
float num = 0;
Match m = null;
while (rg.IsMatch(s) && max > n)
{
m = rg.Match(s);
Num1 = m.Groups["Num1"].Value;
Num2 = m.Groups["Num2"].Value;
CalcChar = m.Groups["CalcChar"].Value;
n1 = Convert.ToSingle(Num1);
n2 = Convert.ToSingle(Num2);
num = calculat(n1, n2, CalcChar);
s = s.Replace(m.Groups[0].Value, num.ToString());
n++;
}
expression = s;
}
void BracketCalculate(ref string expression)
{
string s = expression.Trim();
if (string.IsNullOrEmpty(s)) return;
string CalculateExp = "";
int n = 0;
Match m = null;
while (bracketRg.IsMatch(s) && max > n)
{
m = bracketRg.Match(s);
CalculateExp = m.Groups["CalculateExp"].Value;
Level_Calculate(calcLevel1, ref CalculateExp);
Level_Calculate(calcLevel2, ref CalculateExp);
s = s.Replace(m.Groups[0].Value, CalculateExp);
n++;
}
expression = s;
}
float calculat(float num1, float num2, string CalculateChar)
{
float v1 = 0;
if (string.IsNullOrEmpty(CalculateChar)) return v1;
CalculateChar = CalculateChar.Trim();
switch (CalculateChar)
{
case "+":
v1 = num1 + num2;
break;
case "-":
v1 = num1 - num2;
break;
case "*":
v1 = num1 * num2;
break;
case "/":
v1 = num1 / num2;
break;
case "%":
v1 = num1 % num2;
break;
}
return v1;
}
}
