How can I convert std::string matrix to matrix of integer vectors?

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I have a large number that is initialized by a multidimensional string array and I need to do arithmetic operations on the elements of the array. I implemented the arithmetic operations with vectors but before that, I need to convert the multidimensional string array to a multidimensional vector.

C++

<pre>
//Work out the first ten digits of the sum of the following one-hundred 50-digit numbers.
//The number is in the main()

#include <iostream>
#include <string>
#include <vector>



std::vector<int>addition(std::vector<int>&left, std::vector<int>&right)
{
    int carry=0;
    if(left.size()==right.size())
    {
        for(int i=left.size()-1; i>=0; i--)
        {
            if(i==0)
            {
                left[i]=left[i]+right[i]+carry;
                break;
            }
            left[i]=(left[i]+right[i]+carry);
            carry=left[i]/10;
            left[i]=left[i]%10;

        }

    }
    if(left.size()>right.size())
    {
        int right_size=right.size()-1;
        for(int i=left.size()-1; i>=left.size()-right.size(); i--)
        {
            left[i]=left[i]+right[right_size]+carry;
            carry=left[i]/10;
            left[i]=left[i]%10;
            right_size--;
        }

        for(int i=right.size()-1; i>=0; i--)
        {
            left[i]=left[i]+carry;
        }
    }

    if(right.size()>left.size())
    {
        int left_size=left.size()-1;
        for(int i=right.size()-1; i>=right.size()-left.size(); i--)
        {
            right[i]=right[i]+left[left_size]+carry;
            carry=right[i]/10;
            right[i]=right[i]%10;
            left_size--;
        }
        for(int i=left.size()-1; i>=0; i--)
        {
            right[i]=right[i]+carry;
        }
    }


}

///NEXT STEPS
//1)conversion of numbers matrix to int matrix is needed
std::vector<std::vector<int>>numbers(std::vector<std::vector<std::string>>str_numbers)
{
    std::vector<std::string>left;

    int left_row=0;
    for(int col=0; col<50; col++)
    {
        std::string num=str_numbers[left_row][col];
        left[col]=num-'0';
    }

    for(int row=0; row<100; row++)
    {
        for(int col=0; col<50; col++)
        {

        }
    }
}


int main()
{
    std::vector<int>left{1,4,5,7,2,1,5};
    std::vector<int>right{2,2,1,4};

    //75778645
    std::string number[100]= {
            {"37107287533902102798797998220837590246510135740250"},
            {"46376937677490009712648124896970078050417018260538"},
            {"74324986199524741059474233309513058123726617309629"},
            {"91942213363574161572522430563301811072406154908250"},
            {"23067588207539346171171980310421047513778063246676"},
            {"89261670696623633820136378418383684178734361726757"},
            {"28112879812849979408065481931592621691275889832738"},
            {"44274228917432520321923589422876796487670272189318"},
            {"47451445736001306439091167216856844588711603153276"},
            {"70386486105843025439939619828917593665686757934951"},
            {"62176457141856560629502157223196586755079324193331"},
            {"64906352462741904929101432445813822663347944758178"},
            {"92575867718337217661963751590579239728245598838407"},
            {"58203565325359399008402633568948830189458628227828"},
            {"80181199384826282014278194139940567587151170094390"},
            {"35398664372827112653829987240784473053190104293586"},
            {"86515506006295864861532075273371959191420517255829"},
            {"71693888707715466499115593487603532921714970056938"},
            {"54370070576826684624621495650076471787294438377604"},
            {"53282654108756828443191190634694037855217779295145"},
            {"36123272525000296071075082563815656710885258350721"},
            {"45876576172410976447339110607218265236877223636045"},
            {"17423706905851860660448207621209813287860733969412"},
            {"81142660418086830619328460811191061556940512689692"},
            {"51934325451728388641918047049293215058642563049483"},
            {"62467221648435076201727918039944693004732956340691"},
            {"15732444386908125794514089057706229429197107928209"},
            {"55037687525678773091862540744969844508330393682126"},
            {"18336384825330154686196124348767681297534375946515"},
            {"80386287592878490201521685554828717201219257766954"},
            {"78182833757993103614740356856449095527097864797581"},
            {"16726320100436897842553539920931837441497806860984"},
            {"48403098129077791799088218795327364475675590848030"},
            {"87086987551392711854517078544161852424320693150332"},
            {"59959406895756536782107074926966537676326235447210"},
            {"69793950679652694742597709739166693763042633987085"},
            {"41052684708299085211399427365734116182760315001271"},
            {"65378607361501080857009149939512557028198746004375"},
            {"35829035317434717326932123578154982629742552737307"},
            {"94953759765105305946966067683156574377167401875275"},
            {"88902802571733229619176668713819931811048770190271"},
            {"25267680276078003013678680992525463401061632866526"},
            {"36270218540497705585629946580636237993140746255962"},
            {"24074486908231174977792365466257246923322810917141"},
            {"91430288197103288597806669760892938638285025333403"},
            {"34413065578016127815921815005561868836468420090470"},
            {"23053081172816430487623791969842487255036638784583"},
            {"11487696932154902810424020138335124462181441773470"},
            {"63783299490636259666498587618221225225512486764533"},
            {"67720186971698544312419572409913959008952310058822"},
            {"95548255300263520781532296796249481641953868218774"},
            {"76085327132285723110424803456124867697064507995236"},
            {"37774242535411291684276865538926205024910326572967"},
            {"23701913275725675285653248258265463092207058596522"},
            {"29798860272258331913126375147341994889534765745501"},
            {"18495701454879288984856827726077713721403798879715"},
            {"38298203783031473527721580348144513491373226651381"},
            {"34829543829199918180278916522431027392251122869539"},
            {"40957953066405232632538044100059654939159879593635"},
            {"29746152185502371307642255121183693803580388584903"},
            {"41698116222072977186158236678424689157993532961922"},
            {"62467957194401269043877107275048102390895523597457"},
            {"23189706772547915061505504953922979530901129967519"},
            {"86188088225875314529584099251203829009407770775672"},
            {"11306739708304724483816533873502340845647058077308"},
            {"82959174767140363198008187129011875491310547126581"},
            {"97623331044818386269515456334926366572897563400500"},
            {"42846280183517070527831839425882145521227251250327"},
            {"55121603546981200581762165212827652751691296897789"},
            {"32238195734329339946437501907836945765883352399886"},
            {"75506164965184775180738168837861091527357929701337"},
            {"62177842752192623401942399639168044983993173312731"},
            {"32924185707147349566916674687634660915035914677504"},
            {"99518671430235219628894890102423325116913619626622"},
            {"73267460800591547471830798392868535206946944540724"},
            {"76841822524674417161514036427982273348055556214818"},
            {"97142617910342598647204516893989422179826088076852"},
            {"87783646182799346313767754307809363333018982642090"},
            {"10848802521674670883215120185883543223812876952786"},
            {"71329612474782464538636993009049310363619763878039"},
            {"62184073572399794223406235393808339651327408011116"},
            {"66627891981488087797941876876144230030984490851411"},
            {"60661826293682836764744779239180335110989069790714"},
            {"85786944089552990653640447425576083659976645795096"},
            {"66024396409905389607120198219976047599490197230297"},
            {"64913982680032973156037120041377903785566085089252"},
            {"16730939319872750275468906903707539413042652315011"},
            {"94809377245048795150954100921645863754710598436791"},
            {"78639167021187492431995700641917969777599028300699"},
            {"15368713711936614952811305876380278410754449733078"},
            {"40789923115535562561142322423255033685442488917353"},
            {"44889911501440648020369068063960672322193204149535"},
            {"41503128880339536053299340368006977710650566631954"},
            {"81234880673210146739058568557934581403627822703280"},
            {"82616570773948327592232845941706525094512325230608"},
            {"22918802058777319719839450180888072429661980811197"},
            {"77158542502016545090413245809786882778948721859617"},
            {"72107838435069186155435662884062257473692284509516"},
            {"20849603980134001723930671666823555245252804609722"},
            {"53503534226472524250874054075591789781264330331690"}

    };

    addition(left, right);

}

What I have tried:

I have tried to do it like this: num_array[row][col]=string_vec[row][col]-'0';
it gives a compiler error

Posted 28-Aug-18 18:10pm

Member 13277493

Updated 29-Aug-18 4:16am

v2

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Comments

[no name] 29-Aug-18 0:47am

This is not a very clear question. Converting a string to an int is easy to find using Google. Converting Strings to Numbers in C/C++ - GeeksforGeeks[^] Show the code you are using.

Manish K. Agarwal 29-Aug-18 3:59am

pls provide some sample input and expected output

2 solutions

Solution 1

If you have stored numbers as strings in the array you must convert the in the correct manner. Use the function stod from the string class.

What you have done is a hack to convert a single char to a single number, which is working only for numbers from 0 to 9. So it is better to really understand what some code is doing, and not understanding code is very dangerous. :-O

Posted 28-Aug-18 20:14pm

KarstenK

Comments

Member 13277493 29-Aug-18 10:18am

I needed only the numbers from 0 to 9, yes I think that I did not understand that code good enough

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CPallini · Accepted Answer · 2018-08-28T23:37:00

You may use the istringstream[^] class to perform the string to number conversion. E.g.

C++

#include <iostream>
#include <sstream>
#include <vector>

using namespace std;

int main()
{
  // the bidimensional vector of strings (string representation of integers)
  vector < vector < string > > sv { { "10", "11", "12", "13" }, { "-1", "+1", "0", "2" }};

  vector < vector < int > > iv; // the bidimensional vector of integers we have to fill

  // fill the vector of integers
  for ( const auto & row : sv)
  {
    iv.push_back( vector <int>() );
    for ( const auto & v : row )
    { // convert string to integer using an instance of the 'istringstream class'
      istringstream iss(v);
      int i; 
      iss >> i;
      iv.back().push_back(i);
    }
  }

  // perform a simple operation on numeric values, let's double all the integers
  for (auto & row : iv)
    for (auto & x : row) x *= 2;


  // report new values
  for (const auto & row : iv)
  {
    for (const auto & x : row)
      cout << x << " ";
    cout << endl;
  }
}