Converting char array to int

Question

#include <QtCore/QCoreApplication>
#include<iostream>
#include<cmath>
#include<cstdlib>
#include<cstdio>
#include<cctype>
using namespace std;  
  void test()
    {
        int arr[10];
        int size = 0;
        int i = 0;
        char str[] = "12 45 1666";
        for(;;)
        {
            while(str[i]!='\0' && str[i]==' ')i++;
            if(str[i]=='\0')return;
            arr[size] = 0;
            while(str[i]!='\0' && str[i]!=' ')
            {
                if(!isdigit(str[i]))
                {
                    cout <<str[i]<<" - Not a number!"<<endl;
                    return;
                }
                arr[size]=arr[size]*10+(str[i]-48);
                i++;
            }
            size++;
        }
        for(int k = 0;i<size;k++)
        {
            cout <<arr[k]<<endl;
        }

    }

    int main(int argc, char *argv[])
    {
        QCoreApplication a(argc, argv);
        test();
        return a.exec();
    }

Here I'm trying to write a programm which convert string of figures and spaces to numeral array, but there is a problem it doesn't output. What could cause this problem. I'm a begginer to c++ so critics is welcome.

1) char str[] -> std::string or std::array<char>. 2) I highly encourage you to learn how to use a debugger — Fureeish
– Fureeish, Commented Jan 17, 2018 at 17:02
I just began to learn c++ and don't konw how to use dynamical arrays, but thanks — Alex Delarge
– Alex Delarge, Commented Jan 17, 2018 at 17:12
please don't edit your question so that the given answers becomes incorrect. — default
– default, Commented Jan 17, 2018 at 17:21

François Andrieux · Accepted Answer · 2018-01-17 20:11:01Z

1

return leaves the current function. The only way out of your infinite loop is by leaving the entire function, meaning you always skip the output. Use break instead or supply an appropriate condition to your for(;;) loop.

Though c++ already provides std::stringstream for doing just that.

#include <iostream>
#include <sstream>
#include <string>

int main()
{
    std::stringstream stream("12 45 1666");
    int result;

    // Reads from the stream until it's exhausted or fails
    while (stream >> result)
    {
        std::cout << result << '\n';
    }
    return 0;
}

edited Jan 17, 2018 at 20:11

answered Jan 17, 2018 at 17:02

François Andrieux

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Comments

Alex Delarge · Accepted Answer · 2018-01-17 17:18:20Z

0

    for(int k = 0;k<size;k++)
    {
        cout <<arr[k]<<endl;
    }

problem was here just changed 'i' on 'k'.

answered Jan 17, 2018 at 17:18

Alex Delarge

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1 Comment

Bob__ Over a year ago

Good catch, but it's not the only problem.

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