为什么减去人数C测试结果“0”的字符重新presenting？ [英] Why does subtracting '0' in C result in the number that the char is representing?

问题描述

有人能解释为什么这个工程？

Can someone explain why this works?

char c = '9';
int x = (int)(c - '0');

为什么减去一个char结果的ASCII code'0'是该字符重新presenting多少？

Why does subtracting '0' from an ascii code of a char result the number that that char is representing?

推荐答案

由于炭都重新由若干'0'psented $ P $是第一次这一切。

Because the char are all represented by a number and '0' is the first of them all.

放在桌子的下面你看到的：

'0' => 48
'1' => 49


'9' => 57.

结果：（'9' - 0 ）= （57 - 48）= 9

As a result: ('9' - '0') = (57 − 48) = 9

的来源： http://www.asciitable.com 的

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