Thread: files & streams

Hey ladies and gents I am having a little problem with my code
here it is

Code:

#include <iostream>	                      // cin, cout
#include <fstream>	                       // ifstream, ofstream
#include <string>                     // string, getline()
#include <cassert>                    // assert()
#include <cfloat>                     // DBL_MIN and DBL_MAX
using namespace std;

int main()
{
	cout << "This program computes the longest and shortest\n"
           "lines in a file, as well as the average number of\n"
           "characters per line.\n\n";
	cout << "Enter the name of the input file: ";
	string inputFileName;
	getline(cin, inputFileName); 
	cin.get();
	ifstream inStream;                        //  to the input file,
    inStream.open(inputFileName.data());      //  establish connection,
                 //  and check for success
	char ch;
	unsigned int i=0,line=0, minLine=0, minChars=65535, maxLine=0, maxChars=0, totChars=0;
	i = 0;
	ch = cin.get();
	while (ch != EOF)
	{ /* Read until EOF is reached */
		i++;    /* Count the characters*/
		ch = cin.get();
	if ( ch=='\n')
	{
		line++; /* increment when a newline is found*/
		totChars += i-1; /* Correction for \n (newline) character*/

		if (i<minChars)
		{
			minChars = i;
			minLine = line;
		}
		else if (i>maxChars || minChars>maxChars)
		{
			maxChars = i;
			maxLine = line;
		}

		i = 0;
	}
	}
	cout << "The Input file has: "<< line <<", lines\n";
	cout << "The average number of characters per line is: " << (totChars/(float)line);
	cout << "Line: " << minLine <<" is the shortest line with: " << minChars << " characters\n";
	cout << "Line: " << maxLine <<" is the longest line with: " << maxChars << " characters\n";
	return 0;
}

it is supposed to read a txt file count the characters in each line then display the line number and length of the shortest and longest lines in the file na dthe average number of characters per line. but it just displays the first cout statement and then asks for file name and that is it. can anyone help

close() file?

So are you reading from console or a file?

--
Mats

I had put the curly braces in the wrong place i fixed it now it asks for the file and after three enters it will display the cout statement however my values are all wrong. Can someone please help me?

Code:

#include <iostream>	                      // cin, cout
#include <fstream>	                       // ifstream, ofstream
#include <string>                     // string, getline()
#include <cassert>                    // assert()
#include <cfloat>
#include <conio.h>					// DBL_MIN and DBL_MAX
using namespace std;

int main()
{
	cout << "This program computes the longest and shortest\n"
           "lines in a file, as well as the average number of\n"
           "characters per line.\n\n";
	cout << "Enter the name of the input file: ";
	string inputFileName;
	getline(cin, inputFileName); 
	cin.get();
	ifstream inStream;                        //  to the input file,
    inStream.open(inputFileName.data());      //  establish connection,
												//  and check for success
	char ch=cin.get();;
	unsigned int i = 0,line = 0, minLine = 0, minChars = 65535, maxLine = 0, maxChars = 0, totChars = 0;
	
	while (ch != EOF)
	{								// Read until EOF is reached 
		i++;						// Count the characters
		ch = cin.get();
	if ( ch == '\n')
	{
		line++;						//increment when a newline is found
		totChars += i-1;			// Correction for \n (newline) character
		if (i<minChars)
			{
				minChars = i;
				minLine = line;
			}
		else if (i > maxChars || minChars > maxChars)
			{
				maxChars = i;
				maxLine = line;
			}

		i = 0;
		}
	
	cout << "The Input file has: "<< line <<", lines." << endl;
	cout << "The average number of characters per line is: " << (totChars/(float)line)<< endl;
	cout << "Line: " << minLine <<" is the shortest line with: " << minChars << " characters." << endl;
	cout << "Line: " << maxLine <<" is the longest line with: " << maxChars << " characters." << endl;
	
	return 0;
	}
}

Originally Posted by matsp

So are you reading from console or a file?

--
Mats

a file called test1.txt that has like four lines with various amounts of characters basically garbage sentences.

So why is your code inside the loop of "while (ch != EOF)" reading from "cin"?

--
Mats

Your cout statements now seem to be in your while loop. Dont do that. Move them after/outside it. Proper indentation would help other people see whats going on easier.

You could also calcualte totChars at the end of the prog as i-line.

[edit] Assuming you dont reset i at each new line[/edit]

Originally Posted by gunghomiller

Code:

inStream.open(inputFileName.data());      //  establish connection,
                                                //  and check for success

data() gives a string that is not null terminated. you want c_str().

but the real problem is that you don't "check for success".

Originally Posted by matsp

So why is your code inside the loop of "while (ch != EOF)" reading from "cin"?

--
Mats

i thought that while the file i.e ch is not i.e != the end of file it will continue with the body of the program is that the wrong statement?

Let me explain AGAIN: You are reading "ch" from "cin" inside your big while-not-eof-loop. That is not the file you've just opened, it is the console. Should you type a lot of stuff on the keyboard, hitting enter a few times now and again and then hit CTRL-Z (on windows, if you are using Linux you should use "Ctrl-D" instead), then I suspect your program will output some sort of meaningfull data... But you probably don't really want it to do that, as you are reading a filename from the console, and it's kind of meaningless to do that when you read the rest of the data from the console. Is that more clear?

--
Mats

yes, unfortunately i dont know exactly what to do with this program to make it perform like it is supposed to.

Originally Posted by gunghomiller

yes, unfortunately i dont know exactly what to do with this program to make it perform like it is supposed to.

You probably need to understand a bit better how you use your stream objects then, don't you?

"cin" is a "instream" that has been opened by the system to the console. You don't want to read from the console, so you will need to use another instream. Would that be a good enough clue without me actually writing the code for you?

--
Mats

you mean istream

Originally Posted by robwhit

you mean istream

Yes, of course I do. It's gone midnight, fingers are tired... :-)

--
Mats

unfortunately everything that i try doesnt work I dont want the code just tell me the line it is in I have been working on this thing for like 5 days now. just a little help would be great