CODEWITHSUNDEEP
c++loopswhile-loop
MagicKriss
MagicKriss

Reputation: 1

Staying in while loop

I don't know why, but my program keeps exiting while loop ( the one inside "if" statement)

the input file contains "abc abb ca" and this should put "abc" and "abb" into one (stack_arr[0]) stack and "ca" into different one ( stack_arr[2])

   fin.get(ch);
   while (fin)
    {
        if((int)ch>=97 && (int)ch<=122)
        {
            x=(int)ch-97;

            while(fin && (int)ch>=97 && (int)ch<=122)
           {
               stack_arr[x].push(ch);
               fin.get(ch);
           }
        }

        fin.get(ch);
    }

but it only puts all the 'a' in one stack, all the 'b' in another and so on... i found out that in inner while loop it enters, does one cycle, but does not stay. I cannot understand why is it so.

Upvotes: 0

Views: 259

Answers (1)

Michael
Michael

Reputation: 58427

Instead of your current approach you could make use of the STL (after all, you are programming in C++) to create a more sparse structure containing the different strings:

std::ifstream fin("test.txt", std::ios_base::in);
std::map<char, std::vector<std::string>> stack;
std::string token;
while (getline(fin, token, ' ')) {
    if (!stack.count(token[0])) {
        stack[token[0]] = {};
    }
    stack[token[0]].push_back(token);
}
fin.close();

// Print the contents
for (auto& e : stack) {
    std::cout << "key = " << e.first << "\n";
    for (auto& s : e.second) {
        std::cout << s << "\n";
    }
}

If I run this with the following in test.txt:

abc abb ca
ccb kw

I get the following output:

key = a
abc
abb
key = c
ca
ccb
key = k
kw

Some people might frown at the use of std::map, and if performance is a major concern then perhaps you should be looking at other classes. I just picked a simple implementation.

Upvotes: 1

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