How to apply mask to string in C/C++? [closed]

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I've been asigned with a homework, but I don't know what to do exactly.

Input file is randomly generated from letter from 'a' to 'z'. User will type a mask only with 0/1, for example 011011, where 1 means vowel and 0 means consonant.

Output will be all matches found in input that match the user-given mask (for example for 011011 output will be abbezz).

Any idea how to make this? I don't ask for code, but only for easiest way how to make this possible in c/c++.

Thanks

Answer 1

Map the string to 0/1 according to the rules you have and search for substrings in the new string that match the mask.

Answer 2

My understanding is that the requirements are to find all sequences of letters that match the mask. Given the mask: 010 (consonant, vowel, consonant)
Here are the matches for a couple of words:

"are" - fail, first character is a vowel.  
"mat" - pass, 'm' is a consonant, 'a' is a vowel, 't' is a consonant.  
"mate" - fail, too many letters.  

You will need to have some functions that test a letter for vowel or consonant.

Also consider using a state machine. If a test fails, you want to go back to the starting state.

Write down your algorithm first, step by step. Come up with a few test cases to verify your algorithm. After algorithm works, code it up. Use your same test cases for verifying the program.

Answer 3

I still do not know exactly what you are trying to accomplish, but maybe it helps to know that once you have your input in a std::string, you can iterate over the characters using iterators and any algorithm. Here is an example with std::for_each:

#include <algorithm>
#include <iostream>
#include <string>

void applyMask(std::string::reference aCharacter)
{
    // apply your mask here, character by character

    if ('a' == aCharacter) {
        aCharacter = 'A';
    }
}

int main()
{
    std::string s("stackoverflow");

    std::for_each(s.begin(), s.end(), &applyMask);

    std::cout << s << std::endl;
}

You might want to have a look at std::transform, e.g. http://www.cplusplus.com/reference/algorithm/transform/