Question

For example, if I’m doing a for loop such as follows:

assume the string has been made into a char array already

for(i=0;i<somestring.length;i++)

 somestring[i] = somestring[i] + i;

why doesn’t the previous work?

Answer 1

The result of char + int is an int – so you’d need to cast to char:

char[] charArray = text.toCharArray();
for (int i = 0; i < charArray.length; i++) {
    charArray[i] = (char) (charArray[i] + i);
}

Or use the implicit conversion available when using +=:

char[] charArray = text.toCharArray();
for (int i = 0; i < charArray.length; i++) {
    charArray[i] += i;
}

However, generally performing arithmetic on characters is a bad idea. Bear in mind that you can easily end up with unprintable characters this way. What are you trying to achieve?