[C++] Help finishing code..STUCK - Tilted Forum Project Discussion Community

Scape · 10-30-2005, 05:08 PM

Hi, I have this program it goes through 2 input files then outputs their contents into another file and the outputs are saposta be sorted in alphabetical order. The probelm is one file is shorter than the other and as my program is now it sorts just fine untill it hits the eof of one of the files before the other then its messed up. Heres my code so far

Quote:

#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;

int main()
{
char input1[100];
char input2[100];
char inputFile1[50];
char inputFile2[50];
char outputFile[50];

ifstream inFile;
ifstream inFile2;
ofstream outFile;

cout << "Please enter the name of the first input file: ";
cin >> inputFile1;
inFile.open(inputFile1);
if(inFile.fail())
{

while(inFile.fail())
{
inFile.clear();
cout << "File not found try again: ";
cin >> inputFile1;
inFile.open(inputFile1);

}
}

cout << "Please enter the name of the second input file: ";
cin >> inputFile2;
inFile2.open(inputFile2);
if(inFile2.fail())
{
while(inFile2.fail())
{
inFile2.clear();
cout << "File not found try again: ";
cin >> inputFile2;
inFile2.open(inputFile2);

}
}

cout << "Please enter the name of the output file: ";
cin >> outputFile;
outFile.open(outputFile);

inFile.getline(input1, 101);
inFile2.getline(input2, 101);
while(!inFile.eof() || !inFile2.eof())
{

if(strcmp(input1,input2) > 0)
{
outFile << input2 << endl;
outFile << input1 << endl;
}

else if(strcmp(input1,input2) < 0)
{
outFile << input1 << endl;
outFile << input2 << endl;
}

inFile.getline(input1, 101);
inFile2.getline(input2, 101);
}

inFile.close();
inFile2.close();
cout << "Done\n";

return 0;

}

nukeu666 · 10-30-2005, 06:06 PM

your problem looks to be here

inFile.getline(input1, 101);
inFile2.getline(input2, 101);
}

itll try getting a newline even tho eof has been reached
replace it like this
if infile.eof=false then getline
else print all of infile2 and quit
similarly for infile2

BAMF · 10-31-2005, 02:44 PM

The output wont be alphabetical. You may want to read everything into a container class, sort it, and then write the output file.

C++ container classes should have sort functions built in, so that step becomes 1 line.

For example,
infile1=
aa
ab
ac
infile2=
bb
bc
bd

Your output, I believe, would be
aa
bb
ab
bc
ac
bd
Since you only compare adjacent lines.

BAMF · 10-31-2005, 02:46 PM

Here is a link to an introduction to the C++ STL (standard template library)
http://www.topcoder.com/index?t=features&c=feat_082803

Pragma · 10-31-2005, 03:24 PM

What you'll probably want to use is merge-sort to organize the data. I believe the STL has containers to help with merge-sort.

Zyr · 11-02-2005, 02:04 AM

Yeah, you'll have to read all of the data in, then sort it. At the moment, you're just comparing adjacent lines like BAMF said.

As a general note, you'll want to be checking EOF before you start reading lines, to stop it going off the end.

Quote:

inFile.getline(input1, 101);
inFile2.getline(input2, 101);
while(!inFile.eof() || !inFile2.eof())
{
...
inFile.getline(input1, 101);
inFile2.getline(input2, 101);
}

should be

while(!inFile.eof() || !inFile2.eof())
{
inFile.getline(input1, 101);
inFile2.getline(input2, 101);
...
}
or something.

n0nsensical · 11-02-2005, 02:58 AM

You also have a potential buffer overflow by passing 101 as the buffer size parameter to istream::getline, which should be 100, the size of your buffers. Also, if you use code tags instead of quote tags you can include the whitespace so reading the code isn't painful.

This is almost ridiculously easy if you use STL strings and vectors as you can sort everything with one statement eg:

Code:

string s;
vector<string> v;
while (getline(inFile, s))
	v.push_back(s);
while (getline(inFile2, s))
	v.push_back(s);
sort(v.begin(), v.end());
for (unsigned i = 0; i < v.size(); ++i)
	outFile << v[i] << endl;

#include <algorithm>, <string>, and <vector> in addition.

Jinn · 11-02-2005, 03:43 AM

Call me a java fanboi, but thats ^^^ why I HATE C++.

Pragma · 11-02-2005, 05:29 AM

You Java fanboy! C++ forever! (Though to be honest, I'm not a huge fan of C++ - I'm a C/Perl man myself).

10-30-2005, 06:06 PM	#2 (permalink)
nukeu666 Junkie Location: India	your problem looks to be here inFile.getline(input1, 101); inFile2.getline(input2, 101); } itll try getting a newline even tho eof has been reached replace it like this if infile.eof=false then getline else print all of infile2 and quit similarly for infile2 __________________ Why did the Comp. Engineer get X-mas and Halloween mixed up? Because Oct(31) == Dec(25)

10-31-2005, 03:24 PM	#5 (permalink)
Pragma I am Winter Born Location: Alexandria, VA	What you'll probably want to use is merge-sort to organize the data. I believe the STL has containers to help with merge-sort. __________________ Eat antimatter, Posleen-boy!

11-02-2005, 02:58 AM	#7 (permalink)
n0nsensical Junkie Location: San Francisco	You also have a potential buffer overflow by passing 101 as the buffer size parameter to istream::getline, which should be 100, the size of your buffers. Also, if you use code tags instead of quote tags you can include the whitespace so reading the code isn't painful. This is almost ridiculously easy if you use STL strings and vectors as you can sort everything with one statement eg: Code: string s; vector<string> v; while (getline(inFile, s)) v.push_back(s); while (getline(inFile2, s)) v.push_back(s); sort(v.begin(), v.end()); for (unsigned i = 0; i < v.size(); ++i) outFile << v[i] << endl; #include <algorithm>, <string>, and <vector> in addition.

11-02-2005, 03:43 AM	#8 (permalink)
Jinn Lover - Protector - Teacher Location: Seattle, WA	Call me a java fanboi, but thats ^^^ why I HATE C++. __________________ "I'm typing on a computer of science, which is being sent by science wires to a little science server where you can access it. I'm not typing on a computer of philosophy or religion or whatever other thing you think can be used to understand the universe because they're a poor substitute in the role of understanding the universe which exists independent from ourselves." - Willravel

11-02-2005, 05:29 AM	#9 (permalink)
Pragma I am Winter Born Location: Alexandria, VA	You Java fanboy! C++ forever! (Though to be honest, I'm not a huge fan of C++ - I'm a C/Perl man myself). __________________ Eat antimatter, Posleen-boy!

10-31-2005, 02:44 PM	#3 (permalink)
BAMF Crazy	The output wont be alphabetical. You may want to read everything into a container class, sort it, and then write the output file. C++ container classes should have sort functions built in, so that step becomes 1 line. For example, infile1= aa ab ac infile2= bb bc bd Your output, I believe, would be aa bb ab bc ac bd Since you only compare adjacent lines.

10-31-2005, 02:46 PM	#4 (permalink)
BAMF Crazy	Here is a link to an introduction to the C++ STL (standard template library) http://www.topcoder.com/index?t=features&c=feat_082803