CODEWITHSUNDEEP
c++stringvector
CuriousToLearn
CuriousToLearn

Reputation: 153

how to make use of STL's for better result and performance in this issue

I have some set of strings in format : country/currency/minimum_amount

For example:

US/USD/18
US/EUR/20
DE/USD/22
GB/EUR/19

Let's say i have drop downs each for country, currency and minimum amount. Once i select the country, i should get the possible combination of currency and min amount from the above set of strings.

ex. Once i select country as US in dropdown_1, then currency(dropdown) should display - USD and EUR and min_amt - 18 and 20.\ ex. 2: Once i select Currency as USD in dropdown_2, then country(dropdown) should display - US and DE and min_amt - 18 and 22.. similarly for the third drop down as well.

My solution, Lets assume i have these specific strings in a vector(name - myvector), then I'm retrieving the strings using:

std::string str2("US"); // i need the strings that has country as US
string credt_fin_str;

for (unsigned j=0; j<myvector.size(); j++)
{
    credt_fin_str = myvector.at(j);
    std::size_t found = credt_fin_str.find(str2);

    if(found != string::npos)
    {
        std::cout<<"creditfin found:"<<credt_fin_str<<std::endl;
    }

}

Output: 

US/USD/18
US/EUR/20
DE/USD/22

Since i using string::find, it displays even "USD" as it contains "US" but it shouldn't be for my use case.

can anyone suggest a better solution to this use case so that i can improve the result and performance.

Upvotes: 0

Views: 65

Answers (1)

noisy cat
noisy cat

Reputation: 3065

I'd use std::map.

Map each country name to vector of possible combinations. Typical workflow for this goes as follow:

  1. Parse input string
  2. Store parsing results
  3. Query storage container

So, start with structure for results:

struct CurrencyVal
{
    string currency;
    int minimum_ammount;
};

It will be stored in the vector for each country. This represents single entry like USD/18 and is not related to any country.

Now, lets make some space for storing it:

std::map<string,vector<CurrencyVal>> dropdowns;

It will map any country to list of possible CurrencyVal values. Lets now parse the input vector. Lets say the input vector is vector<string> input.

//Helper function, note the pos is passed by reference to modify it
string parseToToken(string& str, int& pos, char delim)
{
    string result="";
    for (; pos<str.length(); pos++)
    {
        if (str[pos] == delim)
            break;
        result+=str[pos];
    }
    pos++; //Skip the token
    return result;
}

for (unsigned i=0; i<input.size(); i++)
{
    int pos = 0;
    string country;
    CurrencyVal value;

    country = parseToToken(input[i],pos,'/');
    value.currency = parseToToken(input[i],pos,'/');

    //stoi from <string> in C++11, if you are not using c++11, try with atoi(input[i].substr(pos).c_str())
    value.minimum_ammount = stoi(input[i].substr(pos)); 

    //Store the results
    dropdowns[country].push_back(value);
}

That's all. Now we can query this struct like this:

vector<CurrencyVal> allForUs = dropdowns["US"];
for (unsigned i = 0; i < allForUs.size(); i++)
    cout << allForUs[i].country << " - " << allForUs[i].minimum_ammound << endl;

If you have any questions post a comment so I can improve this answer.

Upvotes: 2

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