PLEASE HELP A NOVICE WITH C++. How do i make this code output to a .txt file?

How do I make this code output/debug to a .txt file?

Here is the code:

#include <iostream>
using namespace std;


#define k 100 //force constant= 100 kcal/(mol*A^2)
#define m 16 //mass= 16 Daltons


float x;
float v;
float a; //acceleration
float t; //time
int z;
float dt;

int main ()
{
t=0;
int n;
cout << "Enter the Number of Iterations "<<"\n";
cin >> n;
z=1;
cout<< "Enter Initial Postion:"<<"\n";
cin >> x;
cout<< "Enter Initial Velocity:"<<"\n";
cin >> v;
cout<< "Enter Time Step: "<<"\n";
cin>>dt;
cout<<"t,x"<<"\n";

while (z<n)
{
a= -k*x/m;
x= x + v*dt + .5* a*dt*dt;
v=v+a*dt;
t=t+dt;
cout<<t;
cout<<" , ";
cout<<x<<"\n";
cout<<" ";

z=z+1;
}
system("pause");

return 0;
}

Input/Output with files

And using your email id as your user name will certainly pull a lot of spam to your mail box.

Ya haha, but i am kinda confused on how to have the loop's results written to the txt file? I have already read that page, it is not really helping. Can you be more tell me where to place the codings?

a. Please use code tags, while posting the code, its very hard to read unformulated code (also a bit rude to the people who are willing to you help you, but you are not willing to help them).

b. Open file stream before your while loop and close it after the loop. In the body of the loop, everywhere you have used cout, use the file stream along side (as explained in the link). In the end, the output file would be same as the output that you'll get at console.

Oh sorry about that, I completely forgot. I will do my best to use code tags. I made the adjustments but the program is stopping before the Loop. AKA at: cout<<"t,x"<<"\n"; What am I missing?

//Euler Code for Simple Harmonic Motion

#include <iostream>
#include <fstream> //Stream class to both read and write from/to files.
using namespace std;


#define k 100 //force constant= 100 kcal/(mol*A^2)
#define m 16 //mass= 16 Daltons


float x;
float v;
float a; //acceleration
float t; //time
int z;
float dt;

int main ()
{
t=0;
ofstream myfile; //stream class to write on files
myfile.open ("euler.txt"); //open file euler.txt (WHERE IS THIS SUPPOSED TO BE LOCATED?
int n;
cout << "Enter the Number of Iterations "<<"\n"; //input number of iterations
cin >> n;
z=1;
cout<< "Enter Initial Postion:"<<"\n"; //input initial position
cin >> x;
cout<< "Enter Initial Velocity:"<<"\n"; //input initial velocity
cin >> v;
cout<< "Enter Time Step: "<<"\n"; //input time step
cin>>dt;
cout<<"t,x"<<"\n"; // identify data as time, poition

while (z<n) //loop
{
a= -k*x/m; //formula for acceleration
x= x + v*dt + .5* a*dt*dt; //formula for position
v=v+a*dt; //formula for velocity
t=t+dt; //formula for time
myfile << t; //Display New Time
myfile<<" , "; //Spacing
myfile<<x<<"\n"; //Display New Position
myfile<<" ";

z=z+1;
}

system("pause");
myfile.close(); //close file
return 0;
}

Quote:

---

Originally Posted by [email protected]

Oh sorry about that, I completely forgot. I will do my best to use code tags. I made the adjustments but the program is stopping before the Loop. AKA at: cout<<"t,x"<<"\n"; What am I missing?

//Euler Code for Simple Harmonic Motion

#include <iostream>
#include <fstream> //Stream class to both read and write from/to files.
using namespace std;


#define k 100 //force constant= 100 kcal/(mol*A^2)
#define m 16 //mass= 16 Daltons


float x;
float v;
float a; //acceleration
float t; //time
int z;
float dt;

int main ()
{
t=0;
ofstream myfile; //stream class to write on files
myfile.open ("euler.txt"); //open file euler.txt (WHERE IS THIS SUPPOSED TO BE LOCATED?
int n;
cout << "Enter the Number of Iterations "<<"\n"; //input number of iterations
cin >> n;
z=1;
cout<< "Enter Initial Postion:"<<"\n"; //input initial position
cin >> x;
cout<< "Enter Initial Velocity:"<<"\n"; //input initial velocity
cin >> v;
cout<< "Enter Time Step: "<<"\n"; //input time step
cin>>dt;
cout<<"t,x"<<"\n"; // identify data as time, poition

while (z<n) //loop
{
a= -k*x/m; //formula for acceleration
x= x + v*dt + .5* a*dt*dt; //formula for position
v=v+a*dt; //formula for velocity
t=t+dt; //formula for time
myfile << t; //Display New Time
myfile<<" , "; //Spacing
myfile<<x<<"\n"; //Display New Position
myfile<<" ";

z=z+1;
}

system("pause");
myfile.close(); //close file
return 0;
}

---

What happened to do your best using code tags?

This is the best commenting/code tagging I can do. I made the adjustments but the program is stopping before the Loop. AKA at: cout<<"t,x"<<"\n"; What am I missing?

//Euler Code for Simple Harmonic Motion

#include <iostream>
#include <fstream> //Stream class to both read and write from/to files.
using namespace std;


#define k 100 //force constant= 100 kcal/(mol*A^2)
#define m 16 //mass= 16 Daltons


float x; //position
float v; //velocity
float a; //acceleration
float t; //time
int z;
float dt; //time step

int main () //main program
{
t=0; //time starts
ofstream myfile; //stream class to write on files
myfile.open ("euler.txt"); //open file euler.txt (WHERE IS euler.txt SUPPOSED TO BE LOCATED?
int n; //initiate number of iterations (loops)
cout << "Enter the Number of Iterations "<<"\n"; // number of iterations
cin >> n; //input number of iterations
z=1;
cout<< "Enter Initial Postion:"<<"\n"; //initial position
cin >> x; //input initial position
cout<< "Enter Initial Velocity:"<<"\n"; //initial velocity
cin >> v; //Input initial velocity
cout<< "Enter Time Step: "<<"\n"; //time step
cin>>dt; //input time step
cout<<"t,x"<<"\n"; // identify data as time, poition

while (z<n) //loop initiate
{
a= -k*x/m; //formula for acceleration
x= x + v*dt + .5* a*dt*dt; //formula for position
v=v+a*dt; //formula for velocity
t=t+dt; //formula for time
myfile << t; //Display New Time in file
myfile<<" , "; //Spacing
myfile<<x<<"\n"; //Display New Position in file
myfile<<" ";

z=z+1;
}

system("pause");
myfile.close(); //close file
return 0;
}

[code]code here[/code] will preserve your code indentation making it easier to read.

Quote:

---

Originally Posted by [email protected]

This is the best commenting/code tagging I can do.

---

If you don't know what a certain term means, there's little point in just guessing the meaning. Either search or just ask.
What you added to your code are called comments.
Code tags is something you add in your post on this forum that will help to preserve the indentation of the code to make it readable. See http://forums.codeguru.com/announcement.php?f=7.

How is this?? Thanks for the tips. But,

I made the adjustments but the program is stopping before the Loop. AKA at: cout<<"t,x"<<"\n"; What am I doing wrong in the code

//Euler Code for Simple Harmonic Motion

Code:

---

#include <iostream>
#include <fstream>                //Stream class to both read and write from/to files.
using namespace std;


#define k 100                        //force constant= 100 kcal/(mol*A^2)
#define m 16                          //mass= 16 Daltons


float x;                                //position
float v;                                //velocity
float a;                                //acceleration
float t;                                //time
int z;
float dt;

int main ()
{
        t=0;                                                        //start time
        ofstream myfile;                                //stream class to write on files
        myfile.open ("euler.txt");                //open file euler.txt (WHERE IS euler.txt SUPPOSED TO BE LOCATED?
        int n;
        cout << "Enter the Number of Iterations "<<"\n";        //input number of iterations
        cin >> n;
        z=1;
        cout<< "Enter Initial Postion:"<<"\n";                //input initial position
        cin >> x;
        cout<< "Enter Initial Velocity:"<<"\n";                //input initial velocity
        cin >> v;
        cout<< "Enter Time Step: "<<"\n";                //input time step
        cin>>dt;       
        cout<<"t,x"<<"\n";                                                // identify data as time, poition

        while (z<n)                                                //loop
        {
        a= -k*x/m;                                                //formula for acceleration
        x= x + v*dt + .5* a*dt*dt;                //formula for position
        v=v+a*dt;                                                //formula for velocity
        t=t+dt;                                                        //formula for time
        myfile << t;                                        //Display New Time
        myfile<<"        ,  ";                                //Spacing
        myfile<<x<<"\n";                                //Display New Position
        myfile<<" ";
        z=z+1;
        }

        system("pause");
        myfile.close();                                        //close file
        return 0;
}

---

BUMP anyone?

Try to setup through the debugger and see how the flow of your program, along with the values of each variable. Most likely following check is not being satisfied.

Code:

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while (z<n)

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Following links can help you with debugging.

Mastering Debugging in Visual Studio 2010 - A Beginner's Guide
Tutorial - Debugging C++ in Visual Studio 2010 part (1/3)
Tutorial - Debugging C++ in Visual Studio 2010 (part 2/3)
Tutorial - Debugging C++ in Visual Studio 2010 part (3/3)

But how does the code know where euler.txt is? im confused where/if i identify the location of the file...

my debugger says:

Warning 1 warning C4244: '=' : conversion from 'double' to 'float', possible loss of data Line 39

Quote:

---

Originally Posted by [email protected]

my debugger says:

Warning 1 warning C4244: '=' : conversion from 'double' to 'float', possible loss of data Line 39

---

Its not the debugger, its the compiler. Please go through the links I provided above. They'll give you good understanding to begin debugging your program.

Quote:

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But how does the code know where euler.txt is? im confused where/if i identify the location of the file...

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You can make a search in your system and find out where exactly it is (most likely, right next to your project file).

Oh, I got it, thank you all very much for all your time

--AM