如何将 integer 转换为向量，然后将该向量转换为 C++ 中的字符串

Question

I want to take an integer and turn it into an array and then store it into a string in C++. But I do not know how to turn an integer into an array and then store it into a string. I am still learning C++, so help me, please. That's how I want it to be done:

#include<iostream>
#include<vector>

using namespace std;

int main()
{
  int number = 3215;

  //store the number into vector
  vector<int> numbers;
  //vector[0]=3
  //vector[1]=2
  //vector[2]=1
  //vector[5]=5

  //and then store it into string
  string str;
  //like this
  //str=3215

  return 0;
}

Please help me and show the code as well with explanation

Edit: I have some data to work with integer values with every digit which I can solve my own but for that, I need to first turn the integer into vector and return it as a string. THat's why I want to know how to turn integer into vector first and the that vector into string

Answer 1

The easiest is: std::to_string(yourNum);

If you do need the steps:

std::vector<int> res;

int num;
std::cin >> num;

while(num>0)
    {
    res.insert(res.begin(),num%10);
    num/=10;
    }

and then

std::stringstream result;
std::copy(res.begin(), res.end(), std::ostream_iterator<int>(result, ""));

Answer 2

Since you insist on placing the integers in a vector first and then converting them to string later (when needed?), this can be a solution:

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


int main( )
{
    std::string number;
    std::cin >> number;

    std::vector<int> numbers;
    numbers.reserve( number.length( ) );

    for ( const auto digit : number )
    {
        numbers.push_back( digit - '0' );
    }

    std::cout << "\nElements of vector: ";

    for ( const auto digit : numbers )
    {
        std::cout << digit << ' ';
    }

    std::cout << "\nElements of vector converted to `std::string`: ";

    for ( const auto num : numbers )
    {   
        std::string num_str { std::to_string( num ) };
        std::cout << num_str << ' ';
    }

    std::cout << '\n';
}

Sample I/O:

1234

Elements of vector: 1 2 3 4
Elements of vector converted to `std::string`: 1 2 3 4

Answer 3

You are asking for a set of conversion functions, probably something like the code below . The ASCII codes of the digits are in sequential order , therefore transforming a digit character to a digit means subtracting '0' from it.

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cassert>

std::vector<int> convert(const std::string& s)
{
  std::vector<int> r;
  std::transform(s.begin(), s.end(), std::back_inserter(r), [](auto e) {return e - '0'; });
  return r;
}

std::string convert(const std::vector<int>& v)
{
  std::string r;
  std::transform(v.begin(), v.end(), std::back_inserter(r), [](auto e) {return e + '0'; });
  return r;
}

std::vector<int> convert(const int n)
{
  return convert(std::to_string(n));
}

int main()
{
  auto v = convert(3215);
  auto s = convert(v);
  assert(s == "3215");
}

Answer 4

Here you are:

#include <iostream>
#include <vector>
#include <cmath>
#include <string>
#include <algorithm>
#include <iterator>

int main() {
    int n;
    std::cin >> n;
    std::vector<int> split(static_cast<int>(std::log10(n)) + 1);
    auto royal_10 = split.rbegin();
    auto cpy{ n };
    do {
        *royal_10++ = cpy % 10;
    } while ((cpy /= 10) != 0);
    std::string ret;
    ret.reserve(split.size());
    std::transform(split.cbegin(), split.cend(), std::back_inserter(ret),
        [](int const dig) { return dig + '0'; });
    return 0;
}

Answer 5

1)vector in c++ has vector object.push_back(); // which push data(any type) to vector array 2) using an iterator function you can retrieve that data and by dereferencing(*i) you can receive that data in original form (which you had pushed) 3) use stringstream class or to_string() method to convert into string

//code `

#include<vector>
#include<iostream>

int main()
{
 int number=1234;
 string str;
 vector <int> obj;
 obj.push_back(number);
 for(auto i= obj.begin(); i!= obj.end();i++)
 {
  str = to_string((*i));
  cout << end << str;
 }
}

`