I need to solve the logic of this code..

Question

1.00/5 (2 votes)

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Here is below the code that I need and have to understand what it does..Give me your ideas about it please..
str1 = "ABCD"
str2 = "ACDS"
str3 = "KLMN"

C++

int getUnique(char str1[],char str2[],char str3[],char arr[])
{
    int i,k,temp[26];

    for(i = 0 ; i<26 ; temp[i]=0 , ++i);
        for(i = 0 ; str1[i] ; ++i)
            temp[str1[i] - 'A'] = 1;

    for(i = 0 ; str2[i] ; ++i)
        temp[ str2[i] - 'A'] = 1 ;

    for(i = 0 ; str3[i] ; ++i)
        temp[str3[i] - 'A'] = 1;

    for(i = k = 0 ; i<26 ; ++i)
        if(temp[i])
            arr[k++] = i + 'A';
        
    arr[k] = '\0';

    return k;
}

Posted 14-Oct-12 5:14am

Sabri M

Updated 14-Oct-12 5:46am

v3

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Comments

[no name] 14-Oct-12 11:20am

What about it?

[no name] 14-Oct-12 11:23am

I dont know what It does. Its just a part of my project that I need to understand to use.

[no name] 14-Oct-12 11:28am

You mean you copied some random bit of code from somewhere on the internet and you don't know what it does and you want someone to teach you how to write code? Or do you mean that you wrote a bunch of code and you have no idea what it is that you wrote?

[no name] 14-Oct-12 11:30am

I copied it from somewhere on the internet. But I dont get what It does well. And its a part of my project , works correctly but I failed to understand whether what It does.

Thomas Daniels 14-Oct-12 11:35am

It worked correctly. But if you copied from the internet for your project,
so you need to know what it does, otherwise you didn't add it to your project!

Sergey Alexandrovich Kryukov 14-Oct-12 21:48pm

Same thing: why did you decide to copy "from somewhere on the internet". "somewhere in the internet" is not really trusty source of information.
--SA

Sergey Alexandrovich Kryukov 14-Oct-12 21:47pm

This is not a productive approach? Learning programming is reading on language and programming techniques and them trying to write your own code. It's not really helpful to read some code having no explanation what it is supposed to do.
--SA

2 solutions

Solution 3

Just run it! Or you can debug the code yourself.

Posted 14-Oct-12 5:48am

icerlion

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CPallini · Accepted Answer · 2012-10-14T10:48:00

Quote:
for(i = 0 ; i<26 ; temp[i]=0 , ++i);

Assigns zero to every (26) items of temp.

Quote:
for(i = 0 ; str1[i] ; ++i)
temp[str1[i] - 'A'] = 1;

for(i = 0 ; str2[i] ; ++i)
temp[ str2[i] - 'A'] = 1 ;

for(i = 0 ; str3[i] ; ++i)
temp[str3[i] - 'A'] = 1;

Assigns one to the element of temp[i] having index correpondig to the letters of the passed strings, that is

"ABCD" => temp[0]=temp[1]=temp[2]=temp[3]=1
"ACDS" => temp[0]=temp[2]=temp[3]=temp[18]=1
...

Quote:
for(i = k = 0 ; i<26 ; ++i)
if(temp[i])
arr[k++] = i + 'A';

Builds the string arr using only the letters corresponding to index of non-zero temp items. That is if temp[i] == 1 => append character[i] to arr
(e.g temp[0] == 1 => append 'A' to arr).

Quote:
arr[k] = '\0';

return k;

Terminates the arr string and returns arr length.

The overall result is a string containing, in alphabetic order just one occurrence (hence 'unique') of every character of the three passed string, that is
{"ABCD"," ACDS","KLMN"} => "ABCDKLMNS"

I hope my (brain compiled) code analysis is correct.