[英]How to extract only the letters from string equation Java
I'm trying to extract the letters for the variables in a String "equation". 我正在尝试提取字符串“ equation”中变量的字母。 Then save it to a String array called variables.
然后将其保存到一个名为变量的String数组中。 However, when I print the variables array it is full of "empty containers"
但是,当我打印变量数组时,它充满了“空容器”
How do I make it so that there are no empty spaces in the String[] variables containers? 如何使String []变量容器中没有空格?
String equation = "(a+2)/3*b-(28-c)";
String[] variables = equation.split("[+-/*0-9()]");
for(int i = 0 ; i < variables.length; ++i)
{
System.out.println(variables[i]);
}
Given that your equation may have nested content, a single regex solution may not be optimal. 鉴于您的方程式可能包含嵌套的内容,因此单个正则表达式解决方案可能不是最佳选择。 Instead, I recommend using a pattern matcher, and just scanning the entire equation for letter variables:
相反,我建议使用模式匹配器,并只扫描整个方程以查找字母变量:
String equation = "(a+2)/3*b-(28-c)";
String pattern = "[A-Za-z]+";
Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(equation);
while (m.find()) {
System.out.println("Found a variable: " + m.group(0));
}
Found a variable: a
Found a variable: b
Found a variable: c
Note: This solution assumes you only want the variable names themselves, and you don't care about things like prefixes or coefficients. 注意:此解决方案假定您只希望变量名本身,并且不关心前缀或系数之类的内容。
First replace all non-variable characters( matched by [+*-\\\\/0-9)(]
) with empty string then change it to char array, try this one 首先用空字符串替换所有非可变字符(由
[+*-\\\\/0-9)(]
匹配),然后将其更改为char数组,尝试这个
String equation="(a+2)/3*b-(28-c)";
char[] variables= equation.replaceAll("[+*-\\/0-9)(]","").toCharArray();
for(int i = 0 ; i < variables.length; ++i)
{
System.out.println(variables[i]);
}
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