Thread: what does this mean

im getting the following error on a for loop, what does this mean?

Code:

arning C4552: '<' : operator has no effect; expected operator with side-effect

Can you show the code that causes this error?

well here it is, Andy helped me figure out the reading part of the file but now im trying to get the average of the numbers in the array. so here is what i got so far.

Code:

#include	<iostream.h>
#include	<fstream>
#include	<stdlib.h>
using namespace std;

const int	FILENAMELEN = 30, ARRAYLEN = 4;

// The class array
class	array	{
public: // These functions are avaiable for use outside the class 
	inline int	getsize()	{return(size);}
	int        readarray();
	float findaverage();
	array();

private:
	//Private - available only to member functions
	int	x[ARRAYLEN];
	int	size;
	int j;
	int numbers[20];
	int count;
	float average;
	float sum;
	char filename[FILENAMELEN];
	char inchar;
 
};

//initialization constructor 
array::array(void)
{
	size = 0;
}

int array::readarray()
{
	ifstream infile;
	char filename[FILENAMELEN];
	char inchar;

	cout<<"Enter filename->" <<'\t';
	cin>> filename;
	//openfile
	infile.open(filename);
	//if you cant open the file, print error message
	if (!infile)
	{
		cerr<< "Cannot open " <<filename << endl;
		exit(1);
	}

	//Read the file character
	while (!infile.eof())
	{
		inchar = infile.get(); //this reads in even whitespaces
		cout << inchar; //display it on screen
	}
	infile.close();
	return(0);
}

float array::findaverage()
{
	int j;
	float average;
	sum =0.0;
	for (j<0; j<count; j++)
	{
		sum+=numbers[j];
	}
	average = sum/j;
	cout << "The average is		"<< average <<endl;
	return  0;

}


int	main()
{
	array	myarray;
	myarray.readarray();
	myarray.findaverage();
	return(0);
}

for (j<0; j<count; j++)

ah yes, jesus im blind

ok i corrected the for loop but now the result is ugly, no errors, no warnings, but an ugly wrong result

Code:

 -1. #IND

any ideas?

wait im confused, the numbers contained in the array have not been initialized? I am able to read the array and display the values that is holding, why cant i operate on those values since im able to read them? any ideas how i can go about it then so i can work on those numbers?

>>I am able to read the array and display the values that is holding

Review readarray() again. I see where it reads the material in the file into a single char and displays that char on the screen. But...I don't see where it stores the material read in anywhere, let alone read in an int that could be stored in numbers[] such that the values in numbers[] could then be used in findaverage().

Read the file contents into an int and store the value of the int in numbers[], or better, in my opinion, use a loop to store the value read from the file directly into numbers[], and get rid of !infile.eof() as the conditional of the loop, which is likely to get you into trouble (likely to read in one more value than you had planned on).

i searched on the forums can i use atoi something for this? to convert the char into int? someone give me a few hints please

Once you read your file into an array, you can use atoi to convert it into a number. Here is an example prog to demonstrate this:

Code:

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

using namespace std;

int main() {

    char myString[5] = {'1', ' ', '2', ' ', '3'};
    int myInt[5] = {0};
    int count = 0, sum = 0;

    for(int i = 0; i < 5; i++){
        if(isdigit(myString[i])){
            myInt[count++] = atoi(&myString[i]);
        }
    }
    
    for(int i = 0; i < count; i++){
        sum += myInt[i];
    }
    cout << endl << sum << endl;

    return 0;
}

ok ill work on that. thanks man

for the love of god i still cant figure this out, can someone take a look at my code please the reading is the only thing holding me back, i created another function similiar to findaverage() but if i cant read the numbers then i cant do any work on that either.

Ok here is your while loop where you are reading from the file:

Code:

//Read the file character
while(!infile.eof())
{
     inchar = infile.get(); //this reads in even whitespaces
     cout << inchar; //display it on screen
}
infile.close();

Notice you are not storing your information anywhere. Somewhere in that while loop you are going to need to store the char in inchar into an array or some form of container.

So ask yourself, Do I know how large I need to make the array?(aka how many characters are going to be read from the file)

If you do simply create a char array as one of your private members and then add inchar to it like so:

Code:

 
//Defined in class
char fileInput[fileSize];

//In your read function
int currentChar = 0;

//Read the file character
while(!infile.eof())
{
     fileInput[currentChar] = infile.get(); //this reads in even whitespaces
     cout << fileInput[currentChar]; //display it on screen
     currentChar++;
}
infile.close();

Now if you don't know the size you can either size the array dynamically with the new operator or the easiest way of handling this in C++ is to use a container object such as a vector.

I have a simple prog that loads a file into a vector. Let me know if you want to see it, I am assuming that you want to figure this out for yourself though.