Program to make vowels in string uppercase and change letters to next letter in alphabet(i.e. a->b) not working

Question

how can I solve this. It is supposed to make all vowels in str capitalized and to change each letter in the alphabet to the next letter in the alphabet(i.e. a -> b, or z->a). It keeps returning "str.join is not a function". Any Help? By the way, it's JavaScript.

function LetterChanges(str) { 

  str = str.split("");//split() string into array
  for(var i=0;i<str.length;str++){//for loop that checks each letter
    if(str[i]===/[^a-y]/){
      str=str[i].fromCharCode(str[i].charCodeAt(0) + 1);
        }else if(str[i]==='z'){
          str[i] = 'a';
        }
    if(str[i] === 'a'||'e'||'i'||'o'||'u'){
       str[i] = str[i].toUpperCase();
       }

  }

  //modifies letter by adding up in alphabet
  //capitalizes each vowel
  //join() string


  return str.join(); 
}

// keep this function call here 
// to see how to enter arguments in JavaScript scroll down
LetterChanges(readline());

First you convert `str` to array, then back to a string with `fromCharCode`. You're mutating. It's no longer an array when you do `str.join` — elclanrs, Jan 15 '14 at 17:01
To add to @VisioN's comment, this isn't right either `str[i] === 'a'||'e'||'i'||'o'||'u'` — elclanrs, Jan 15 '14 at 17:01
readline() inputs the value I type into a text bar. It shouldn't affect the rest of it. This is for one of those online coding websites and LetterChanges(readline()); was put into the program by the website. Just ignore it. — Colin Michael Flaherty, Jan 15 '14 at 17:03
This line: 'str=str[i].fromCharCode(str[i].charCodeAt(0) + 1);' is getting error: "TypeError: str[i].fromCharCode is not a function" — Colin Michael Flaherty, Jan 15 '14 at 18:32

score 1 · Accepted Answer · answered Jan 15 '14 at 17:01

1

Ok, you need to read a bit on JavaScript.

This is doesn't do what you think str[i]===/[^a-y]/. You should use str[i].match(/[a-y]/i).

This doesn't do what you think: str[i] === 'a'||'e'||'i'||'o'||'u'. It'll always return true. You'll want this str[i].match(/[aeiou]/i).

answered Jan 15 '14 at 17:01

Simon Boudrias

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Thanks. This helps a lot. And yes, I'm trying to teach myself Javascript. Does === not work when comparing strings? Do I always have to use .match() when comparing strings? – Colin Michael Flaherty Jan 15 '14 at 17:14
@user3196340 String.match() finds the matches in strings against the passed regular expression. === does work when comparing strings, but it compares for equality without type coercion, rather than matching a regex. – Eric Alberson Jan 15 '14 at 17:19

score 1 · Answer 2 · edited May 23 '17 at 12:04

1

There are several logical errors in your code, as described in @Simon Boudrias answer.

However just for self-learning here is an alternative solution for your problem:

str.replace(/[a-z]/g, function(c) {
    return 'aeiou'.indexOf(c) > -1
        ? c.toUpperCase()
        : String.fromCharCode(Math.max(c.charCodeAt(0) % 122 + 1, 97));
});

edited May 23 '17 at 12:04

Community

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1

answered Jan 15 '14 at 17:09

VisioN

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@user3196340 Yeah, more than normal. – VisioN Jan 15 '14 at 17:13

Program to make vowels in string uppercase and change letters to next letter in alphabet(i.e. a->b) not working

2 Answers2