如何计算字符串中char的出现次数？ [英] How do I count the number of occurrences of a char in a String?

问题描述

我有字符串

a.b.c.d

我想以惯用的方式计算'。'的出现次数，最好是单行。

I want to count the occurrences of '.' in an idiomatic way, preferably a one-liner.

（之前我已经把这个约束表达为没有循环，如果你想知道为什么每个人都试图回答而不使用循环）。

(Previously I had expressed this constraint as "without a loop", in case you're wondering why everyone's trying to answer without using a loop).

推荐答案

这个怎么样？它不使用下面的regexp，所以应该比其他一些解决方案更快，并且不会使用循环。

How about this. It doesn't use regexp underneath so should be faster than some of the other solutions and won't use a loop.

int count = line.length() - line.replace(".", "").length();

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