来自文件的C ++ Cin无空格数字

Question

In c++ how do i cin a file of numbers that are not spaced into an array?

For instance 78940725450327458 how could i get those numbers to be placed so that list[0] = 7, list[1] = 8, list[2] = 9 and so on.

Answer 1

std::vector<int> numList;

while(std::cin) {
    char c;
    std::cin >> c;
    if(std::cin.eof())
        break;
    if(c < '0' || c > '9') {
        // handle error
    }
    numList.push_back(c - '0');
}

Answer 2

Make list an array of char s.

cin >> list[0] will then read a single character.

Answer 3

I would suggest you to read all the line into int variable and then do the loop with something like this:

int temp = a % 10;

this will give you last number everytime, be sure to update original number after that and last thing to do is to put it into array, so thats the easy part.

Answer 4

There are many ways to do this. I'd probably do something like the following:

#include <algorithm>
#include <fstream>
#include <iterator>
#include <vector>

int ascii2int(int value) // this could be a lambda instead
{
    return value - '0';
}

int main()
{
    std::vector<int> nums;
    std::ifstream input("euler8Nums.txt");
    if (input)
    {
        // read character digits into vector<int>
        nums.assign(std::istream_iterator<char>(input), std::istream_iterator<char>());
        // transform ascii '0'..'9' to integer 0..9
        std::transform(nums.begin(), nums.end(), nums.begin(), ascii2int);
    }

    // your code here

    return 0;
}