Need help with arrays and file I/O

[dkwan]

I am trying to calculate the average of 4 integers from a text file and then find the maximum and minimum. This is where i have reached...I am having problems to read the integers and calculate the average..

#include <cstdlib>
#include <iostream>
#include <fstream.h>

using namespace std;

int main(int argc, char *argv[])
{   char numbers[100];
    int sum;
    int n,i,firstnum,secondnum,thirdnum,fourthnum,count1,count2;
    int average;
    int min = 0; 
    int max = 0; 
    
    ifstream streamin;
    ofstream streamout;
    if (argc!=3)
       { cerr<< "Usage:Program input_file_output_file\n";
         exit(1);
       }
       
       if(!streamin)
          { cerr <<"Cannot open file!" <<argv[1] <<"for reading" <<endl;
            exit(1);
            }
     if(!streamout)
          { cerr <<"Cannot open file!" <<argv[2] <<"for reading" <<endl;
            exit(1);
            }
     streamin.open(argv[1]);
     
    
    streamin.getline(numbers,100);
    
    
    cout <<"The four integers of the input file are: " << numbers <<endl;
   
   streamout.open(argv[2]);
  
   
   streamin.close();
   streamout.close();

[hsn]

i understand your problem
first put the if statement of streamin after the line where you say streamin.open,
and don't use the if statement of streamout until u define which file streamout is going to use.

your other problem is with getline
you are entering the number 100 as one of the parameters, which means 100 chars from the file. and you only need to read 4 digits not 100.
look through it well

[dkwan]

I have made some changes..The average part is not working..can you tell me if im doing it right..thanks

#include <cstdlib>
#include <iostream>
#include <fstream.h>
#include <stdlib.h>

using namespace std;

int main(int argc, char *argv[])
{   char numbers[11];
    int sum=0;
    int i,;
    int average;
    int min = 0; 
    int max = 0; 
    
    ifstream streamin;
    ofstream streamout;
    if (argc!=3)
       { cerr<< "Usage:Program input_file_output_file\n";
         exit(1);
       }
       
      
     
     streamin.open(argv[1]);
      if(!streamin)
          { cerr <<"Cannot open file!" <<argv[1] <<"for reading" <<endl;
            exit(1);
            }
    
    streamin.getline(numbers,11);
    cout <<"The four integers of the input file are: " << numbers <<endl;
   
   streamout.open(argv[2]);
   if(!streamout)
          { cerr <<"Cannot open file!" <<argv[2] <<"for reading" <<endl;
            exit(1);
            }
  
   for(i=0;i<11;++i)
   {
      sum+=numbers[i];
   }
   
   average=sum/4;
   
   cout<<average;
   
   streamin.close();
   streamout.close();
    
  
       
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

[hsn]

you are reading the input worng
you are reading it into char value and after that you are adding that to a number that will not work.
you have to add a number to a number to char to a number.
try to convert the char into a number
if you have char c='1';
int i =c-'0';
then i==1;
the same thing for any number , this works only for single digit in a char (advicing to to do it for more than one digit in a char);
you can solve it

[hsn]

listen here is a very easy way to solve you question.
you don't need to solve this question by using getline()
you know you have four values
so you create n1,n2,n3,n4 as int.
you know when you use
cin>>s; //where s is a string.
if the input was the scripts
s will be "the" without "scripts".
the operator ">>" will not read after " "(space).
so use ">>" rather than getline();
so you wirte 4 times
streamin>>n1;
streamin>>n2;
streamin>>n3;
streamin>>n4;

then you will have the four values.
and then do the average and summation part
don't forget to use double for average so what ever after . will be their like 2.5 or so.


HOPE i was helpful

regards
hsn

[dkwan]

if you have char c='1';
int i =c-'0';
then i==1;

Can you please explain more about this part..

[dkwan]

Thanks a lot!!!
I have been able to solve it..Great!!

[hsn]

if you have a char c = '3';
int n=c-'0';
n==3;
it is a rule me my self i don't understand how it is working. but it does work i am sure of it.

good luck and i hope i helped you

regards

hsn

[dkwan]

oops..i messed up everything..i thought the solution you gave me was working..i am getting confused..help me please..

[hsn]

oops..i messed up everything..i thought the solution you gave me was working..i am getting confused..help me please..

where are u getting confused exactly?????

[dkwan]

#include <cstdlib>
#include <iostream>
#include <fstream.h>
#include <stdlib.h>

using namespace std;

int main(int argc, char *argv[])
{  string numbers;
    int sum=0;
    int i,n1,n2,n3,n4;
    int average;
    int min = 0; 
    int max = 0; 
    
    ifstream streamin;
    ofstream streamout;
    if (argc!=3)
       { cerr<< "Usage:Program input_file_output_file\n";
         exit(1);
       }
       
      
     
     streamin.open(argv[1]);
      if(!streamin)
          { cerr <<"Cannot open file!" <<argv[1] <<"for reading" <<endl;
            exit(1);
            }
    streamin>>numbers;
    
    
    cout <<"The four integers of the input file are: " << n1 <<n2 <<n3 <<n4 <<endl;
   
   streamout.open(argv[2]);
   if(!streamout)
          { cerr <<"Cannot open file!" <<argv[2] <<"for reading" <<endl;
            exit(1);
            }
  
   
   
   streamin.close();
   streamout.close();
    
       
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

is this the way to do it??i am having problems to read the numbers in the text file

[hsn]

as i told you the operator >> will read a value until a space is faced so if the input is "1 2 3 4" and you said streamin>>n1;
n1==1;
don't use the streamin>>numbe rs;
use it like this
streamin>>n1
streamin>>n2
streamin>>n3
streamin>>n4

by this n1==1,n2==2,n3= =3,n4==4;
it is like using cin;

[dkwan]

i tried it but it is not working!! help me plzzz

[sicarie]

i tried it but it is not working!! help me plzzz

Okay, how is it not working? Are you getting an error? Or do the numbers not come out right? Can we see the code (and the errors, if any)?

[dkwan]

I have the integers 8 55 26 99 in the input file but it is being displayed as 8552699.
i modified the code as hsn asked me..

#include <cstdlib>
#include <iostream>
#include <fstream.h>
#include <stdlib.h>

using namespace std;

int main(int argc, char *argv[])
{  string numbers;
    int sum=0;
    int i,n1,n2,n3,n4;
    int average;
    int min = 0; 
    int max = 0; 
    
    ifstream streamin;
    ofstream streamout;
    if (argc!=3)
       { cerr<< "Usage:Program input_file_output_file\n";
         exit(1);
       }
       
      
     
     streamin.open(argv[1]);
      if(!streamin)
          { cerr <<"Cannot open file!" <<argv[1] <<"for reading" <<endl;
            exit(1);
            }
   streamin>>n1;
   streamin>>n2;
   streamin>>n3;
   streamin>>n4;
    
    
    cout <<"The four integers of the input file are: " ;<< n1 <<n2 <<n3 <<n4 <<endl;
   
   streamout.open(argv[2]);
   if(!streamout)
          { cerr <<"Cannot open file!" <<argv[2] <<"for reading" <<endl;
            exit(1);
            }
  
   
   
   streamin.close();
   streamout.close();
         
    
    system("PAUSE");
    return EXIT_SUCCESS;
}