Why canot this code read and write txt file?

[spring2014]

Dear Friends,
I want this code get "t" 9 times from input.txt at desktop and save the acc(t) results in array [3][3] forms in output.text file in desktop. But while running it shows different than I expect. I made a text file in desktop and wrote:
2
3
4
5
6
7
8
9
10

But this code output is: 10 20 30 40 50 60 70 80 90 100
I want to see the results in
20 30 40
50 60 70
80 90 100
form.


what should I do?

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

int acc(int x)
{
    return (10*x);
}

int main()
{
    const int a = 9;  //reading 9 items from file, assume the file has upto 9 items
    int array[3][3];
    
    ifstream inputFile("C:/users/spring/Desktop/input.txt");  //ive not checked if the file exists
    ofstream outputFile("C:/users/spring/Desktop/output.txt");
    
    //read from file
    int a;
    for(int i = 0; i < 3; i++)
    {
        for(int j = 0; j < 3; j++)
        {
            inputFile>>a;
            array[i][j] = acc(a);
        }
    }
    
    //print to file
    for(int i = 0; i < 3; i++)
    {
        for(int j = 0; j < 3; j++)
        {
            if(i%3 == 0)
                cout<<endl;
            outputFile<<array[i][j]<<setw(4);
        }
    }
    return 0;
}

[Tom56785]

I've corrected your code. It seems that you were over-complicating things a little bit; you didn't really need a 2-dimensional array so I changed it into a single dimensional one.

I tried to keep the code as simple as possible, but if there is something you wish me to explain such as what something does or why I did it then I will be happy to.

Code:

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

int acc(string x)
{
	return (10*stoi(x)); // "stoi" converts a string into an integer
}

int main()
{
	const int a = 9;  //reading 9 items from file, assume the file has upto 9 items
	string array[a];

	ifstream inputFile("C:/users/spring/Desktop/input.txt");  //ive not checked if the file exists
	ofstream outputFile("C:/users/spring/Desktop/output.txt");

	//read from file
	int pos = 0;
	while (!inputFile.eof() && pos <= 9) {
		getline(inputFile, array[pos]);
		pos++;
	}
	inputFile.close();

	//print to file
	for(int i = 0; i < a; i++)
	{
		outputFile << acc(array[i]) << endl;
	}
	outputFile.close();
	return 0;
}

[spring2014]

Thanks a lot. But while running it gives error in lines 9 and 10.

[Tom56785]

Did you put "#include <string>" at the top like I did? If you did then the error will be because one of the lines in the file is not an integer. Other than that, the code works flawlessly for me.

[spring2014]

Yes I put.

[Tom56785]

Is it an error during compilation or is it while the program is actually running?

[spring2014]

The error is this: it says stoi is not declared

6:44:17 **** Incremental Build of configuration Debug for project test 12 ****
Info: Internal Builder is used for build
g++ -O0 -g3 -Wall -c -fmessage-length=0 -o main12.o "..\\main12.cpp"
..\main12.cpp: In function 'int acc(std::string)':
..\main12.cpp:16:19: error: 'stoi' was not declared in this scope
return (10*stoi(x)); // "stoi" converts a string into an integer
^
..\main12.cpp:17:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^

[Tom56785]

If you are using g++ then you have to set the compiler options to support C++11 because "stoi" is a new feature. But other than that there should be no other issues. As long as you include the "string" header and use the "std" namespace as well then you should be fine.

[jlb]

The stox() series of of functions required a recent C++11 compiler.

[spring2014]

Thanks a lot.
Also Do you have any idea how can I change the
10 20 30 40 50 60 70 80 90 100

output to

20 30 40
50 60 70
80 90 100

in my first code?

[Tom56785]

In my code all you have to do is change the "int i = 0" on line 29 into "int i = 1". That would just output all of the lines except the first one.

[spring2014]

The problem is that my compiler does not know stoi
:(

[Tom56785]

What compiler are you using? You can use an alternative compiler such as Eclipse which does support C++11 functions and is also free. If you don't want to use Eclipse then there are plenty of other C++11 compilers hanging around on the internet.

[spring2014]

I use eclipse

[Tom56785]

Have you enabled C++11 support in the project properties?

Try this link:
http://stackoverflow.com/questions/17457069/enabling-c11-in-eclipse-juno-kepler-luna-cdt