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<title>你真棒</title>
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<div style="text-align: center; font-family: 微软雅黑; font-size: 50px; color: #C03; "><strong><em>四则运算</em></strong></div>
<div style="text-align: center; font-family: 微软雅黑; font-size: 15px; color: #C03; "><strong><em>Welcome To User The System</em></strong></div>
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<form name="form1" method="post" action="arithmetic.jsp" >
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<p>选择题目类型：
<input name="elementNum" value="2" type="radio" />2元运算
<input name="elementNum" value="3" type="radio" checked="checked"/>3元运算<br><br>
<strong>题目数量：
<select name="count">
<option>10</option>
<option>20</option>
<option>30</option>
<option>40</option>
<option>50</option>
<option>60</option>
</select>
<br /><br />
限定时间：
<select name="timelimit">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
<option>6</option>
</select>
分钟
<br />
<input name="" type="submit" value="开始答题" style="margin:0 auto;display:block;" />
</strong>
</p>
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public class Arithmetic {
public static void main(String args[]){
System.out.println(arithmetic("2.2+((3+4)*2-22)/2*3.2"));
}
public static double arithmetic(String exp){
String result = parseExp(exp).replaceAll("[\[\]]", "");
return Double.parseDouble(result);
}
/**
* 解析计算四则运算表达式，例：2+((3+4)*2-22)/2*3
*/
public static String parseExp(String expression){
//String numberReg="^((?!0)\d+(\.\d+(?<!0))?)|(0\.\d+(?<!0))$";
expression=expression.replaceAll("\s+", "").replaceAll("^\((.+)\)$", "$1");
String checkExp="\d";
String minExp="^((\d+(\.\d+)?)|(\[\-\d+(\.\d+)?\]))[\+\-\*\/]((\d+(\.\d+)?)|(\[\-\d+(\.\d+)?\]))$";
//最小表达式计算
if(expression.matches(minExp)){
String result=calculate(expression);
return Double.parseDouble(result)>=0?result:"["+result+"]";
}
//计算不带括号的四则运算
String noParentheses="^[^\(\)]+$";
String priorOperatorExp="(((\d+(\.\d+)?)|(\[\-\d+(\.\d+)?\]))[\*\/]((\d+(\.\d+)?)|(\[\-\d+(\.\d+)?\])))";
String operatorExp="(((\d+(\.\d+)?)|(\[\-\d+(\.\d+)?\]))[\+\-]((\d+(\.\d+)?)|(\[\-\d+(\.\d+)?\])))";
if(expression.matches(noParentheses)){
Pattern patt=Pattern.compile(priorOperatorExp);
Matcher mat=patt.matcher(expression);
if(mat.find()){
String tempMinExp=mat.group();
expression=expression.replaceFirst(priorOperatorExp, parseExp(tempMinExp));
}else{
patt=Pattern.compile(operatorExp);
mat=patt.matcher(expression);
if(mat.find()){
String tempMinExp=mat.group();
expression=expression.replaceFirst(operatorExp, parseExp(tempMinExp));
}
}
return parseExp(expression);
}
//计算带括号的四则运算
String minParentheses="\([^\(\)]+\)";
Pattern patt=Pattern.compile(minParentheses);
Matcher mat=patt.matcher(expression);
if(mat.find()){
String tempMinExp=mat.group();
expression=expression.replaceFirst(minParentheses, parseExp(tempMinExp));
}
return parseExp(expression);
}
/**
* 计算最小单位四则运算表达式（两个数字）
* @param exp
* @return
*/
public static String calculate(String exp){
exp=exp.replaceAll("[\[\]]", "");
String number[]=exp.replaceFirst("(\d)[\+\-\*\/]", "$1,").split(",");
BigDecimal number1=new BigDecimal(number[0]);
BigDecimal number2=new BigDecimal(number[1]);
BigDecimal result=null;
String operator=exp.replaceFirst("^.*\d([\+\-\*\/]).+$", "$1");
if("+".equals(operator)){
result=number1.add(number2);
}else if("-".equals(operator)){
result=number1.subtract(number2);
}else if("*".equals(operator)){
result=number1.multiply(number2);
}else if("/".equals(operator)){
result=number1.divide(number2);
}
return result!=null?result.toString():null;
}
}