compilation error multi-character character constant in caesar

Question

The code is:

string plaintext = GetString();
    for (int i = 0, n = strlen(plaintext); i < n; i++)
    {
    printf("%c", plaintext[i]);
        if ((isalpha(plaintext[i])) && (isupper(plaintext[i])))
            {
            int letter = 'plaintext[i]' ;
            int ciphertext = (letter + key) ;
    }

And I get the errors "multi-character character constant" and "character constant too long for its type" for the line

int letter = 'plaintext[i]' ;

What do these mean and how do I fix them?

Answer 1

Simple fix. Look at the line:

int letter = 'plaintext[i]' ;

You are trying to put the integer (ASCII) value of a letter stored at plaintext[i] into the variable letter. The idea is right, but look at what you did. int letter = 'something' ; When you use the single quotes around something, it has to be a single character. If you had used double quotes, it would have had to be a string. So, because you used single quotes, the compiler is treating whatever is between them literally, ( usually described as a literal ) and anything longer than one character is too long.

Fix? drop the single quotes.

int letter = plaintext[i] ;

The compiler will now treat plaintext[i] as the array element that you intended to use.

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