[RESOLVED] File I/O and String question

[captjack]

i have a text file called example.txt and it contains the following lines.

21 squarepants,Spongebob
115 barack,Obama
7 Carter,Mc Farland
227 Abraham Carter,Lincoln

Basically, I have to read into this file, take the last name and capitalize it. I need to have the capitalized last name outputed onto another text file, which i called outfile.
I just started c++ and the class is basically self-teaching. I am not an expert, but i do have 2 approaches to this program. I just need help writing the code.

My first approach is if i can use a substring and take out the string between the first space and the comma. I tried it but when compiling it never seems to work. I feel it has something to do with my syntax. Another possible approach could be if i can clear all the numbers and get the postion of the comma and clear everything after the comma. That way all i have left is a string with just the last name. Well, below is what I have so far. I have included both of my approaches, so someone can correct my code.

Thank You in advance for your help. I would really appreciate it!

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main ()
{

string line, str, str1;
ifstream infile; //object for reading from a file
ofstream outfile; // object for writing to a file
size_t pos;

infile.open ("example.txt", ios::app); //open a file for writing
outfile.open ("results.txt");

if (infile.is_open()) // if file was able to open
{
while (!infile.eof())

cout << (char) infile.get();
getline(infile,line); //print out the lines in the entire file

str1 = line;

//Approach #1
pos = str.find(" "); // position of " " in str
pos = str.find(","); // position of "," in str
str1 = str.substr (" ", ","); // get the string between the first
space and the comma


// Approach #2
pos = str.find(" "); // position of " " in str
pos = str.find(","); // position of "," in str
str2 = str.substr (pos); // get everything after the comma
str2.erase(pos); // erase everything after the comma. Is this line
even correct?

str1=last;
cout << uppercase << last << endl;
outfile << last << endl;

infile.close();
outfile.close();
}
else
{
cout << "Error opening file";
}
return 0;
}

[laserlight]

Your idea to find the position of the space and then the comma is workable, but your implementation is wrong. For example, you are overwriting the pos variable prematurely.

[captjack]

Ya I figured my implementation was wrong. I just started C++.
I can't seem to get it right when implementing with substring.

How would you recommend to do it?

[laserlight]

I would expect something like this:

string line;
while (getline(infile, line))
{
    string::size_type pos1 = line.find(' ');
    if (pos1 != string::npos)
    {
        ++pos1;
        string::size_type pos2 = line.find(',', pos1);
        if (pos2 != string::npos)
        {
            string surname = line.substr(pos1, pos2 - pos1);
            // ...
        }
    }
}

[captjack]

this is what i have so far. The only problem is that it outputs only the last name for the first line and not the last names in the next 3 lines. shouldn't my while loop get the next line and repeat the positions again?



#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main ()
{

string line, str, str1;
ifstream infile; //object for reading from a file
ofstream outfile; // object for writing to a file
size_t pos;

infile.open ("example.txt", ios::app); //open a file for writing
outfile.open ("results.txt");

if (infile.is_open()) // if file was able to open
{

string line;
while (getline(infile, line))
{
string::size_type pos1 = line.find(' '); //pos1 is the position of the first space
if (pos1 != string::npos)
{
++pos1;
string::size_type pos2 = line.find(',', pos1); //pos2 is the position of the comma
if (pos2 != string::npos)
{
string last = line.substr(pos1, pos2 - pos1); //remove everything before the first space
cout << uppercase << last << endl;
outfile << last << endl;
}
}

infile.close();
outfile.close();
}
}
else
{
cout << "Error opening file";
}
return 0;
}