如何用内部包含x10的字符串比较和替换x10变量

Question

我一直在尝试做的事情：

double x10 = 2.4;  
String str = "The value of a variable is x10";  
int c = 0;  
while(c<str.length) #Here digit means a valid Number  
if(str.charAt[c]==digit && str.charAt[c+1]==digit){  
  str.charAt[c] = Double.toString(x10);
}  

所需输出：

The value of a variable is 2.4

问题：

The problem is that it doesn't seems to be comparing 10 in a String,  
so that it can replace the x10 in the string with the value of variable x10.

有没有其他方法可以达到预期目标？

it works fine with variable x(1-9) but when it exceeds x10 & greater it stucks.  
Didn't found anything relevant to my problem.  

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Answer 1

我假设你在C#。您可以使用接受MatchEvaluator委托的Regex.Replace变体。假设您的值是double[] values格式的，并且它们的替换在值上是一次性的(例如，"x1“对应于values[0])，您可以这样做：

var ans = Regex.Replace(str, @"x(\d+)", m => values[Convert.ToInt32(m.Groups[1].Value)-1].ToString());

Answer 2

经过如此多次的尝试，才能达到预期的输出。我终于想出了解决它的方法。

    String str = "x12",str2 = "x1";
    if(str2.matches("x[0-9]{1}")==true){

        int var = Integer.parseInt(str.substring(1,2));
        System.out.println(var);

    }else{
        System.out.println("Not Found!");

    }if(str.matches("x[0-9]{2}")==true){

        int var = Integer.parseInt(str.substring(1,2));
        int var2 = Integer.parseInt(str.substring(2,3));
        var = var * 10 + var2;
        System.out.println(var);

    }else{
        System.out.println("Not Found!");
    }