Subtract int from char : possible lossy conversion int to char

Question

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

How do rotate the char successfully?

Please help!

Answer 1

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.

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);