简单数学方程的正则表达式 [英] regex for simple math equation

问题描述

我想识别整数或小数以及四个简单的操作，分解为标记我无法让小数生效，你能帮忙吗?

I want to recognize integers or decimals and the four simple operations, broken into tokens I can't get the decimal to work, can you please help?

我的注册号是

expression = "2.7 + 3 * (1 + 2)";
String expRegString = "\\d+(\\.\\d+)*|[\\(\\)\\+\\-\\*\\/]";
Pattern expPattern = Pattern.compile(expRegString);
Matcher expMatcher = expPattern.matcher(expression);

while (expMatcher.find()){
    System.out.println(expMatcher.group());
}

给我 "+", "3", "(" , "1", "+" , "2",")"

正确的结果是 "2.7","+", "3", "(" , "1", "+" , "2",")">

推荐答案

您可以尝试删除所有空格，然后在字符 - +<之前或之后的每个位置拆分数据/code> * / ( ).

You can try removing all spaces and then split your data on every place that is before or after characters - + * / ( ).

这应该可以解决问题

String expression = "2.7 + 3 * (1 + 2)";
String[] tokens = expression.replaceAll("\\s+", "").split("(?<=[-+*/()])|(?=[-+*/()])");

for (String token : tokens)
    System.out.println(token);

输出

2.7
+
3
*
(
1
+
2
)

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