CODEWITHSUNDEEP
c++ifstream
parul71625
parul71625

Reputation: 193

How to read integers from a text file containing symbols, numbers and maybe alphabets?

How to read integers from the following text file containing symbols, numbers and maybe alphabets?

I have the following text file 

@
100:20 ;
20:40 ;
#

@
50:30 ;
#

@
10:21:37 ;
51:23 ;
22:44 ;
#

I have tried the following codes :

int main()
{
    std::ifstream myfile("10.txt", std::ios_base::in);

    int a;
    while (myfile >> a)
    {
       std::cout<< a;
    }

    return 0;
}

and 

void main()
{
   std::ifstream myfile("10.txt", std::ios_base::in);
   std::string line;

   while (std::getline(infile, line))
   {
       std::istringstream iss(line);
       int n;
       while (iss >> n)
       {
         std::cout << n ;
       }

    }
}

All I get is a garbage value of int variable (or the initial value if I initialize it )

How to solve this?

Upvotes: 0

Views: 484

Answers (2)

huu
huu

Reputation: 7472

You can try splitting each line into separate tokens delimited by the colon character:

int main()
{
    std::ifstream myfile("10.txt", std::ios_base::in);
    std::string line;

    while (std::getline(myfile, line))
    {
        std::istringstream iss(line);
        std::string token;
        while (std::getline(iss, token, ':'))
        {
            std::istringstream tss(token);
            int n;
            while (tss >> n)
            {
                std::cout << n << std::endl;
            }
        }
    }

    return 0;
}

This should print:

100
20
20
40
50
30
10
21
37
51
23
22
44

As per this comment, I recommend a more robust parsing algorithm that respects the unique structure of your files.

Upvotes: 2

Hcorg
Hcorg

Reputation: 12178

Try skipping bad character one after another

Something like:

while (!in.eof())
{
   int a;
   in >> a;
   if (!in) // not an int
   {
     in.clear(); // clear error status
     in.ignore(1); // skip one char at input
   }
   else
   {
     cout << a;
   }
 }

Upvotes: 0

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