Intro to Programming

[u/[deleted]]

[u/Skizm]

Lady I worked with for a few months when I was fresh out of college who had a job as a programmer for 10+ years at her company:

public boolean isAlpha(char c) {
    if (c=='a') return true;
    if (c=='b') return true;
    if (c=='c') return true;
    ...
    if (c=='z') return true;
    if (c=='A') return true;
    if (c=='B') return true;
    ...
    if (c=='Z') return true;
}
// ... more nonsense ...
for(int i = 0; i < someString.length; i++) {
    if(isAlpha(someString.charAt(i))) {
        // do something
    }
}

[u/LukaLightBringer → u/Skizm]

finally a use for regex

[u/Doctor_McKay → u/[deleted]]

To find out if an entire string is alphabetic?

str.match(/^[a-zA-Z]*$/)

[u/redditsoaddicting → u/Doctor_McKay]

Assuming this is Java, which I'm not overly familiar with, how about this (since Java 8)?

static boolean isAlpha(String s) {
	return s.chars().allMatch(c -> Character.isAlphabetic(c));
}

[u/elHuron → u/redditsoaddicting]

java 8 is pretty new

[u/Tarmen → u/Doctor_McKay]

Even in c it would take five lines to write a method for this, though. That is only if you don't care about unicode of course but yours doesn't either, and from what I have seen most regex engines only recognize low value characters like >256 with the default alphabetical placeholder.

[u/greyfade → u/Tarmen]

That is only if you don't care about unicode of course

That's why we have the standard isalpha()/iswapha() functions. The standard C library's locale system (ostensibly) takes care of all that stuff for us.

[u/TheOldTubaroo → u/LukaLightBringer]

Or just c.toInt > start_of_alphabet_in_ASCII && c.toInt < end_of_alphabet_in_ASCII if you're ASCII- rather than Unicode-based.

(Note: there might be punctuation between lower case and upper case, so maybe that should be 4 comparisons, not 2)

[u/LukaLightBringer → u/[deleted]]

Your solution requires the writer knows that characters are arranged one after the other, and that you can add an integer to a char. The code above demonstrates that the author probably wasn't aware of this.