Method writing with strings

Programming Questions

beastly325

in Programming Questions • 1 year ago

Hey everyone,

I've been trying to write a method which checks the users input (a word) with a list of letters I have stored in a string. If the word entered contains the letters in the string I want it to return true, otherwise false. Below is my futile attempt at it :S

boolean IsMirrorImage(String input){

String mirror = "AHIMOTUVWXYimnouvwx";

for (int i=0; i<input.length(); i++){

input.charAt(i);

if(input.(has any value within String mirror))

return true;

else

return false;

}

I'm wondering if the String mirror is written correctly and what im trying to do with it is actually possible. All help would be appreciated,

Thanks :)

Replies(12)

PhiLho

Re: Method writing with strings

1 year ago

Well, charAt() result should be used, eg. like char c = input.charAt(i);
Moreover, there is a logical fail in your code: if you return whatever the result of your test, you don't loop!
Something working better:

boolean IsMirrorImage(String input)
{
String mirror = "AHIMOTUVWXYimnouvwx";
for (int i = 0; i < input.length(); i++)
{
String charI = input.substring(i, i+1);
print(charI);
if (mirror.contains(charI))
return true;
}
return false;
}
void setup()
{
println(IsMirrorImage(""));
println(IsMirrorImage("z"));
println(IsMirrorImage("Processing"));
println(IsMirrorImage("Whatever"));
println(IsMirrorImage("Blerk"));
}

I take a string instead of a char, because String.contains() wants a string.

Chrisir

Re: Method writing with strings

1 year ago

@ Phi.lho:

Better t est for !contains

return false

And after the loop return true.

Otherwise you leave the func when first letter is correct.

Since lol should Return True [edited]

But lldll or LOL false

@ beastly: please don't delete threads

PhiLho

Re: Method writing with strings

1 year ago

Ah, perhaps I misunderstood the intent of the test.
if(input.(has any value within String mirror))

return true;

seems to imply that it is OK as soon as one letter of mirror is found in input.

I restored the deleted thread. Indeed, it is rude to delete a thread where somebody answered. Better add information to the old thread instead of creating a new one.

Chrisir

Re: Method writing with strings

1 year ago

Thanks!

beastly325

Re: Method writing with strings

1 year ago

My bad, I didn't realise deleting a thread would be a no-no.

Anyways, thank you both for your helpful contributions :)

beastly325

Re: Method writing with strings

1 year ago

So just to clear up any confusion, what I needed was for the method to check if the user input had any of the letters from the string mirror.

So if the user had entered 'LOL' it would return false, because 'LOL' is a palindrome its not quite a mirror image.. A mirror image would be something like 'AXA' or 'xox' (all the letters i have used are in the string mirror)..

Hopefully that clears up any confusion :)

PhiLho

Re: Method writing with strings

1 year ago

" to check if the user input had any of the letters from the string mirror"
Perhaps you mean "if all letters in the user input are in the string mirror"?

So indeed Chrisir was right.

boolean IsMirrorImage(String input)
{
String mirror = "AHIMOTUVWXYimnouvwx";
for (int i = 0; i < input.length(); i++)
{
String charI = input.substring(i, i+1);
print(charI);
if (!mirror.contains(charI))
return false;
}
return true;
}
void setup()
{
println(IsMirrorImage(""));
println(IsMirrorImage("z"));
println(IsMirrorImage("Processing"));
println(IsMirrorImage("wAxAw"));
// Not enough, of course
println(IsMirrorImage("WHAT"));
println(IsMirrorImage("HAMMix"));
}

For true mirror test:

String mirror = "AHIMOTUVWXYimnouvwx";
boolean IsMirrorImage(String input)
{
for (int i = 0; i < input.length(); i++)
{
String charI = input.substring(i, i+1);
print(charI);
if (!mirror.contains(charI))
return false;
}
return true;
}
boolean IsPalindrome(String input)
{
int len = input.length();
for (int i = 0; i < len / 2; i++)
{
char cL = input.charAt(i);
char cR = input.charAt(len - 1 - i);
if (cL != cR)
return false;
}
return true;
}
String[] tests =
{
"",
"z",
"A",
"Processing",
"LOL",
"HannaH",
"HAMMAH",
"wAxAw",
// Not enough, of course
"WHAT",
"HAMMix",
};
void setup()
{
for (String test : tests)
{
println("-" + IsMirrorImage(test));
}
println("\nReal tests\n");
for (String test : tests)
{
println("-" + (IsMirrorImage(test) && IsPalindrome(test)));
}
exit();
}

Chrisir

Re: Method writing with strings

1 year ago

Oh, my bad

lol is true

LOL is false

beastly325

Re: Method writing with strings

1 year ago

I do finally have it working, so thank you to both :). However im not completely 100% sure what the for loop is actually doing.. if someone could break it down for me that would be awesome :D (sorry for being a pain)

for (int i = 0; i < input.length(); i++)
{
String charI = input.substring(i, i+1);
print(charI);
if (!mirror.contains(charI))
return false;
}
return true;
}

Incase someone didn't know what for loop i was talking about.

Chrisir

Re: Method writing with strings

1 year ago

We want to check the word input.

Therefore in the for loop we go through it letter by letter (substring does this, read the help on it).

We store the current letter in the var charl which is type String.

When we find only one letter that is not (the not is expressed by the sign ! ) part of mirror (contains checks this), we can immediately quit and return false.

When the for loop is finished and the line after the for loop is reached, this means not one letter was not part of mirror (incorrect) - all letters were right, so we can return true here.

Remark

The ! before "contains" means not - a logical not.

beastly325

Re: Re: Method writing with strings

1 year ago

Thank you very much for your help Chrisir!

Chrisir

Re: Method writing with strings

1 year ago

You're welcome.

If you have further questions, please ask, I can go into greater detail.

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