Programming Forums > Application Development > C++

codylee270 · Apr 9th, 2006, 6:22 PM

I'm back quickly!

Well, if you read the last massive thread i started, then you'll be on track for where this is going. Basically, I'm doing a program that will read the file i made in the last thread, and then give you some options to change data in it. Before I can get into the fun part of parsing lines and what not, I at least need to get the data from the file. The following is what i have thus far:

(Toggle Plain Text)

#include <iostream>
#include <fstream>
#include <string>
#include <cctype>
#include <iomanip>
#include <vector>
#include <cstdlib>
using namespace std;


int main()
{
	int i=0,j=0,id[10];
	vector<int> years;
	char sex[10];
	float wage[10];
	int yearsworked;
    ifstream infile;
    ofstream outfile;
    string disp1, disp2, filename;
    float holder[10], line;

    cout << "Please input the name of the file you wish to open: " ;
    getline(cin, filename);
    
    infile.open(filename.c_str());
    if(infile.fail())
    {
                      cout <<"\nThe file was not successfully opened." << endl;
                      exit(1);
    }
    getline(infile, disp1);
    getline(infile, disp2);
    
    while(getline( infile, line))
    {
         holder[i] = line;
         i++;
    }
    infile.close();
    
    cout << "\nThe file contained the following:" << endl;
    
    cout << disp1 << endl << disp2 << endl;
    for(j=0; j<10; j++)
    {
             cout << holder[i] << endl;
    }
     
    
    
	system("PAUSE");
	return 0;
}

It gives me the error:
no matching function for call to `getline(std::ifstream&, float&)'
which corresponds to:

(Toggle Plain Text)

while(getline( infile, line))

I was hoping to read in the first to lines which are just labels for the table, and then store the next 10 lines in an array. From there i would extract data from each line and into a corresponding array like the last thread, and alter it that way, but i'll do that part AFTER i can successfully compile this code and read in the file..lol... I'm betting this one is simple.

Ooble · Apr 9th, 2006, 7:02 PM

I believe the getline function will only read into a std::string class, though I could be wrong on that. What we definitely know is that it won't read into a float. However, that's what the iostream operators are for:

(Toggle Plain Text)

while (infile >> line)

DaWei · Apr 9th, 2006, 7:09 PM

Just a small comment on your terminal remark in the last thread: see this check, in your new code?

(Toggle Plain Text)

    if(infile.fail())
    {
                      cout <<"\nThe file was not successfully opened." << endl;
                      exit(1);
    }

cin is an input stream also. There's no reason not to give it the same attention. It's cheap. If you check my examples, I don't do exhaustive error analysis, but I write a small function, something like this:

(Toggle Plain Text)

int OMGBBQ!!!!!1111 (string catastrophe)
{
   cerr << catastrophe << endl;
   return 1;
}

and call it something like this:

(Toggle Plain Text)

   cin >> someVariableRequiringCorrectInput;
   if (!cin.good ()) return OMGBBQ!!!!!1111 ("Bad user!  Bad user!");
   ...
   // more code

Now, as to your current question: did you read the types of arguments required by the various versions of 'getline', and what its return is? You can't coerce your libraries to have things they don't have just out of pure desire. If the writers didn't provide them, and you want them that badly, you have to write the yourself.

codylee270 · Apr 9th, 2006, 7:57 PM

what exactly is cerr. I've seen it, but we haven't been over it.

DaWei · Apr 9th, 2006, 8:09 PM

Standard error, akin to stderr. One gets 3 file handles/pointers by default when the program opens. Standard error typically goes to the console, same as stdout, but they may be separately redirected (as to a log file and an output file), particularly in the case of batch files.

Cache · Apr 9th, 2006, 8:29 PM

I've changed your code to use the 'stringstream' object. While it's still not robust it should give you an idea of how to extract numeric input. The major changes are in bold:

(Toggle Plain Text)

#include <iostream>
#include <fstream>
#include <string>
#include <cctype>
#include <iomanip>
#include <vector>
#include <cstdlib>

#include <sstream>

using namespace std;


int main()
{
	int id[10];
	vector<int> years;
	char sex[10];
	float wage[10];
	int yearsworked;
	ifstream infile;
	ofstream outfile;
	string disp1, disp2, filename, line;

	cout << "Please input the name of the file you wish to open: " ;
	getline(cin, filename);
	
	infile.open(filename.c_str());
	if(infile.fail())
	{
					  cout <<"\nThe file was not successfully opened." << endl;
					  exit(1);
	}
	getline(infile, disp1);
	getline(infile, disp2);
	
	vector<float> holder;
	float temp;
	
	while( getline(infile, line) )
	{
		 stringstream ss ( stringstream::in | stringstream::out );
		 ss << line;
		 ss >> temp;
		 if ( !ss ) { continue; }
		 holder.push_back( temp );
	}
	infile.close();
	
	cout << "\nThe file contained the following:" << endl;
	
	cout << disp1 << endl << disp2 << endl;
	for( int i = 0; i < holder.size(); ++i )
	{
			 cout << holder[i] << endl;
	}
	
	cout << "Press ENTER to exit program. . .";
	cin.sync();
	cin.get();
	return 0;
}

codylee270 · Apr 9th, 2006, 8:27 PM

Well,
I made Ooble's change above, and it now reads the files, and gives me the first 2 lables of the table correctly, but when i try to store the rest to an array, it gives me junk. How should i declare that array and the "line" variable that each line is first stored to so that it gives me exactly what the file contains?

and actually, i changed some code to look like this:

(Toggle Plain Text)

while(infile >> holder[i])
    {
                 i++;
    }

codylee270 · Apr 9th, 2006, 8:36 PM

hey cache,
I still get junk for output, not the actual lines from the file.

Cache · Apr 9th, 2006, 8:39 PM

Like I said, that should give you an idea. I don't know what's in your file.

codylee270 · Apr 9th, 2006, 8:42 PM

this is what's in the file:

(Toggle Plain Text)

Employee ID       Employee Sex         Numeric Wage        Years with Company
-----------       ------------         ------------        ------------------
       6162                  F         $      12.23                       355
    4654654                  M         $      23.60                         6

It easy to get the labels and ----- out and displayed, but I wanted to get the other lines, and get the crap out of em them and store them in separate arrays. But when try to get those lines from a file, it gives me junk.

Apr 9th, 2006, 6:22 PM	#1
codylee270 Unverified User Join Date: Sep 2005 Posts: 209 Rep Power: 0	More fileopen close stuff extending from my last thread! I'm back quickly! Well, if you read the last massive thread i started, then you'll be on track for where this is going. Basically, I'm doing a program that will read the file i made in the last thread, and then give you some options to change data in it. Before I can get into the fun part of parsing lines and what not, I at least need to get the data from the file. The following is what i have thus far: (Toggle Plain Text) #include <iostream> #include <fstream> #include <string> #include <cctype> #include <iomanip> #include <vector> #include <cstdlib> using namespace std; int main() { int i=0,j=0,id[10]; vector<int> years; char sex[10]; float wage[10]; int yearsworked; ifstream infile; ofstream outfile; string disp1, disp2, filename; float holder[10], line; cout << "Please input the name of the file you wish to open: " ; getline(cin, filename); infile.open(filename.c_str()); if(infile.fail()) { cout <<"\nThe file was not successfully opened." << endl; exit(1); } getline(infile, disp1); getline(infile, disp2); while(getline( infile, line)) { holder[i] = line; i++; } infile.close(); cout << "\nThe file contained the following:" << endl; cout << disp1 << endl << disp2 << endl; for(j=0; j<10; j++) { cout << holder[i] << endl; } system("PAUSE"); return 0; } #include <iostream> #include <fstream> #include <string> #include <cctype> #include <iomanip> #include <vector> #include <cstdlib> using namespace std; int main() { int i=0,j=0,id[10]; vector<int> years; char sex[10]; float wage[10]; int yearsworked; ifstream infile; ofstream outfile; string disp1, disp2, filename; float holder[10], line; cout << "Please input the name of the file you wish to open: " ; getline(cin, filename); infile.open(filename.c_str()); if(infile.fail()) { cout <<"\nThe file was not successfully opened." << endl; exit(1); } getline(infile, disp1); getline(infile, disp2); while(getline( infile, line)) { holder[i] = line; i++; } infile.close(); cout << "\nThe file contained the following:" << endl; cout << disp1 << endl << disp2 << endl; for(j=0; j<10; j++) { cout << holder[i] << endl; } system("PAUSE"); return 0; } It gives me the error: no matching function for call to `getline(std::ifstream&, float&)' which corresponds to: (Toggle Plain Text) while(getline( infile, line)) while(getline( infile, line)) I was hoping to read in the first to lines which are just labels for the table, and then store the next 10 lines in an array. From there i would extract data from each line and into a corresponding array like the last thread, and alter it that way, but i'll do that part AFTER i can successfully compile this code and read in the file..lol... I'm betting this one is simple.

Apr 9th, 2006, 7:02 PM	#2
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	I believe the getline function will only read into a std::string class, though I could be wrong on that. What we definitely know is that it won't read into a float. However, that's what the iostream operators are for: (Toggle Plain Text) while (infile >> line) while (infile >> line) __________________ Me :: You :: Them

Apr 9th, 2006, 7:09 PM	#3
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Just a small comment on your terminal remark in the last thread: see this check, in your new code? (Toggle Plain Text) if(infile.fail()) { cout <<"\nThe file was not successfully opened." << endl; exit(1); } if(infile.fail()) { cout <<"\nThe file was not successfully opened." << endl; exit(1); } cin is an input stream also. There's no reason not to give it the same attention. It's cheap. If you check my examples, I don't do exhaustive error analysis, but I write a small function, something like this: (Toggle Plain Text) int OMGBBQ!!!!!1111 (string catastrophe) { cerr << catastrophe << endl; return 1; } int OMGBBQ!!!!!1111 (string catastrophe) { cerr << catastrophe << endl; return 1; } and call it something like this: (Toggle Plain Text) cin >> someVariableRequiringCorrectInput; if (!cin.good ()) return OMGBBQ!!!!!1111 ("Bad user! Bad user!"); ... // more code cin >> someVariableRequiringCorrectInput; if (!cin.good ()) return OMGBBQ!!!!!1111 ("Bad user! Bad user!"); ... // more code Now, as to your current question: did you read the types of arguments required by the various versions of 'getline', and what its return is? You can't coerce your libraries to have things they don't have just out of pure desire. If the writers didn't provide them, and you want them that badly, you have to write the yourself. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Apr 9th, 2006, 8:09 PM	#5
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Standard error, akin to stderr. One gets 3 file handles/pointers by default when the program opens. Standard error typically goes to the console, same as stdout, but they may be separately redirected (as to a log file and an output file), particularly in the case of batch files. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Apr 9th, 2006, 8:29 PM	#6
Cache Hobbyist Join Date: Sep 2005 Posts: 266 Rep Power: 4	I've changed your code to use the 'stringstream' object. While it's still not robust it should give you an idea of how to extract numeric input. The major changes are in bold: (Toggle Plain Text) #include <iostream> #include <fstream> #include <string> #include <cctype> #include <iomanip> #include <vector> #include <cstdlib> #include <sstream> using namespace std; int main() { int id[10]; vector<int> years; char sex[10]; float wage[10]; int yearsworked; ifstream infile; ofstream outfile; string disp1, disp2, filename, line; cout << "Please input the name of the file you wish to open: " ; getline(cin, filename); infile.open(filename.c_str()); if(infile.fail()) { cout <<"\nThe file was not successfully opened." << endl; exit(1); } getline(infile, disp1); getline(infile, disp2); vector<float> holder; float temp; while( getline(infile, line) ) { stringstream ss ( stringstream::in \| stringstream::out ); ss << line; ss >> temp; if ( !ss ) { continue; } holder.push_back( temp ); } infile.close(); cout << "\nThe file contained the following:" << endl; cout << disp1 << endl << disp2 << endl; for( int i = 0; i < holder.size(); ++i ) { cout << holder[i] << endl; } cout << "Press ENTER to exit program. . ."; cin.sync(); cin.get(); return 0; } #include <iostream> #include <fstream> #include <string> #include <cctype> #include <iomanip> #include <vector> #include <cstdlib> #include <sstream> using namespace std; int main() { int id[10]; vector<int> years; char sex[10]; float wage[10]; int yearsworked; ifstream infile; ofstream outfile; string disp1, disp2, filename, line; cout << "Please input the name of the file you wish to open: " ; getline(cin, filename); infile.open(filename.c_str()); if(infile.fail()) { cout <<"\nThe file was not successfully opened." << endl; exit(1); } getline(infile, disp1); getline(infile, disp2); vector<float> holder; float temp; while( getline(infile, line) ) { stringstream ss ( stringstream::in \| stringstream::out ); ss << line; ss >> temp; if ( !ss ) { continue; } holder.push_back( temp ); } infile.close(); cout << "\nThe file contained the following:" << endl; cout << disp1 << endl << disp2 << endl; for( int i = 0; i < holder.size(); ++i ) { cout << holder[i] << endl; } cout << "Press ENTER to exit program. . ."; cin.sync(); cin.get(); return 0; }

Apr 9th, 2006, 7:57 PM	#4
codylee270 Unverified User Join Date: Sep 2005 Posts: 209 Rep Power: 0	what exactly is cerr. I've seen it, but we haven't been over it.

Apr 9th, 2006, 8:27 PM	#7
codylee270 Unverified User Join Date: Sep 2005 Posts: 209 Rep Power: 0	Well, I made Ooble's change above, and it now reads the files, and gives me the first 2 lables of the table correctly, but when i try to store the rest to an array, it gives me junk. How should i declare that array and the "line" variable that each line is first stored to so that it gives me exactly what the file contains? and actually, i changed some code to look like this: (Toggle Plain Text) while(infile >> holder[i]) { i++; } while(infile >> holder[i]) { i++; }

Apr 9th, 2006, 8:36 PM	#8
codylee270 Unverified User Join Date: Sep 2005 Posts: 209 Rep Power: 0	hey cache, I still get junk for output, not the actual lines from the file.

Apr 9th, 2006, 8:39 PM	#9
Cache Hobbyist Join Date: Sep 2005 Posts: 266 Rep Power: 4	Like I said, that should give you an idea. I don't know what's in your file.

Apr 9th, 2006, 8:42 PM	#10
codylee270 Unverified User Join Date: Sep 2005 Posts: 209 Rep Power: 0	this is what's in the file: (Toggle Plain Text) Employee ID Employee Sex Numeric Wage Years with Company ----------- ------------ ------------ ------------------ 6162 F $ 12.23 355 4654654 M $ 23.60 6 Employee ID Employee Sex Numeric Wage Years with Company ----------- ------------ ------------ ------------------ 6162 F $ 12.23 355 4654654 M $ 23.60 6 It easy to get the labels and ----- out and displayed, but I wanted to get the other lines, and get the crap out of em them and store them in separate arrays. But when try to get those lines from a file, it gives me junk.

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Programming Forums > Application Development > C++

More fileopen close stuff extending from my last thread!