如何将单个字符转换为int [英] How to convert a single char into an int

问题描述

我有一个数字字串，例如123456789，我需要提取每一个他们在计算中使用它们。我可以通过索引访问每个字符，但是如何将它转换为一个int？

I have a string of digits, e.g. "123456789", and I need to extract each one of them to use them in a calculation. I can of course access each char by index, but how do I convert it into an int?

我已经查看了atoi（），但它需要一个字符串论据。因此，我必须将每个字符转换成一个字符串，然后调用atoi就可以了。有没有更好的方法？

I've looked into atoi(), but it takes a string as argument. Hence I must convert each char into a string and then call atoi on it. Is there a better way?

推荐答案

你可以利用的事实，字符编码的数字都是从48 '0'）到57（'9'）。这适用于ASCII，UTF-x和几乎所有其他编码（）。

You can utilize the fact that the character encodings for digits are all in order from 48 (for '0') to 57 (for '9'). This holds true for ASCII, UTF-x and practically all other encodings (see comments below for more on this).

因此，整数值对于任何数字是数字少于'0'（或48）。

Therefore the integer value for any digit is the digit less '0' (or 48).

char c = '1';
int i = c - '0'; // i is now equal to 1, not '1'

与

char c = '1';
int i = c - 48; // i is now equal to 1, not '1'

但是我发现第一个 c - '0'更易读。

However I find the first c - '0' far more readable.

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