Question

I am trying in vain to find a way to parse a text file stored in a string object. The format of the string is as follows:

...
1  45
1  46
1  47
2  43
2  44
2  45
...

I am trying to iterate over the whole string, grab each line, and then split the string by the first integer and the second integer for further processing. However, doing something like this doesn’t work:

string  fileContents;

string::iterator index;

for(index = fileContents.begin(); index != fileContents.end(); ++index)
{
   cout << (*index);       // this works as expected

   // grab a substring representing one line of the file
   string temp = (*index); // error: trying to assign const char to const char*
}

I am trying to find a way to do this, but so far I haven’t had any luck.

Answer 1

Use istringstreams and std::getline() to obtain the integers from each line:

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

int main()
{
    std::istringstream in("1 45\n1 47\n");
    std::string line;
    while (std::getline(in, line))
    {
        std::istringstream nums(line);
        int i1, i2;
        if (nums >> i1 && nums >> i2)
        {
            std::cout << i1 << ", " << i2 << "\n";
        }
    }
    return 0;
}

See demo at http://ideone.com/mFmynj .