从 char 中减去 int:int 到 char 的可能有损转换 [英] Subtract int from char : possible lossy conversion int to char

问题描述

我试图在典型的密码学密钥问题中从 char 中减去 int，但我在以下语句中遇到了上述错误:

I am trying to subtract int from char in a typical cryptography key question but I am running into the above mentioned error in the following statements:

char ch = (int)encrypted_message.charAt(i) + key[index];
if (ch > 122)
    ch = (int)ch - 26;

key[] 数组保存密钥的数字，类型为 int.

key[] array holds digits of the key and is of type int.

如何成功旋转字符?

请帮忙！

推荐答案

int 比 char 大，但是你的操作结果是int(然后将其存储在 char 中).因此，编译器警告您可能会丢失将 int 值存储到 char 变量中的信息.

int is bigger than char, but the result of your operation is typed int (which you're then storing in a char). So the compiler is warning you you might lose information storing an int value into a char variable.

相反，确保结果是 char，这有点麻烦，因为 + 和 - 带有 char 值导致 int，所以我们必须转换:

Instead, ensure the result is a char, which is a bit of a pain because + and - with char values results in an int, so we have to cast:

char ch = (char)(encrypted_message.charAt(i) + key[index]);
if (ch > 122)
    ch = (char)(ch - 26);

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