Thread: printf problem

printf("%f", myDouble);

EDIT - and C is a subset of C++ so it's all good

I think printf is deprecated in C++, I didnt touch it Cos I start with C++, lol~

also how do you add a blank space using printf(); and what would be the statement for if it was an integer instead.

Originally posted by niroopan
also how do you add a blank space using printf();

you must be missing the basic concept of printf here. printf takes your format string and inserts the variables you give it in to it where the various % codes are. so to print a double

printf ("%f", mydouble);

to print a double with a space after it

printf ("%f ", mydouble);

also, you really shouldnt be using freopen here, theres no need to. just use

fprintf (myfile, "%f ", mydouble);

(that is after you fopen() myfile of course)

Code:

double foo=3.14127;
printf("the value of foo is %f",foo);
printf("  ");
printf("which also happens to be the value of PI\n");
// or to put it all together

printf("the value of foo is %f  which also happens to be the value of PI\n",foo);

stop using freopen.
and do something like this (code may not be 100% accurate)

fout << "Student " << studcount << studaverage << '%' << endl;

or with fprintf

fprintf (myfile "Student %i %.2f%%\n", studcount, studaverage);

why redirect stdout when you could use fopen or fstream classes which would make this a piece of cake.
On the whole its probably not a good idea to mix c and c++ i/o routines. stick to one or the other.

you mean to say you know how to use freopen() but not fopen()????

Originally posted by niroopan
the real code is this,

Code:

//Author: Gavinn Niroopan//
//Program Name: ngsummary.h//
//Revision Date: 2002-10-11//
//Explanation: to use variables and loopibf structures display a summary,the following assignment will demonstrate a program structure, code layout and use logic structure//

#include <iostream.h>	//allows cout statement//
#include <iomanip.h>   	//allows decimal formatting, setiosflags()//
#include <conio.h>     	//allows clrscr() and getch()//
#include <string.h>    	//allows strcpy()//
#include <time.h>      	//allows the call of time function//
#include <stdio.h>      //allows printf statement//

int main(void)
{
	int studcountmax, year;
   double term1, term2, studaverage, classtotal;

   time_t t=time(NULL); //time function//
								//Fowler Statement//
   setiosflags(ios::right|ios::fixed);
   							//Will display the time//
   cout <<setw(79)<<ctime(&t)<<endl;
   cout<<setw(79)<<"Gavinn Niroopan"<<endl;
   cout<<setw(79)<<"2002-10-11"<<endl;
   cout<<setw(79)<<"Mr. Slack"<<endl;
   cout<<setw(79)<<"ICS 3MO-A"<<endl;
   gotoxy(32,8); 			//moves cursor to location (x,y) on screen//
   cout<<"Summary Program"<<endl;
   gotoxy(32,9);
   cout<<"~~~~~~~~~~~~~~~"<<endl;
   							//"for" loop for spacing//
   	for(int i= 1;i <=6;i++)
      	cout<<endl;
   cout<<"Explanation:"<<endl;
	cout<<"~~~~~~~~~~~"<<endl<<endl;
   cout<<"\tTo create a program which will use variables and looping structures"<<endl;
   cout<<"\tto display a summary sheet. The following assignment will demonstrate"<<endl;
   cout<<"\ta program structure, code layout and use logic structures. The program"<<endl;
   cout<<"\tThe program will use data derived from the user and date acquired from"<<endl;
   cout<<"\the system at time of execution."<<endl;

   getch();					//Pause screen//
   clrscr();				//clear screen//

   cout<<ctime(&t)<<endl<<endl;
   gotoxy(29,4);
   cout<<"Class Summary Analysis"<<endl;
   gotoxy(29,5);
   cout<<"~~~~~~~~~~~~~~~~~~~~~~"<<endl<<endl;
   cout<<"\tHow many students are being processed:     ";
   cin>>studcountmax;
   cout<<"\tWhat school year is being processed:       ";
   cin>>year;

   clrscr();				//clear screen//

   for(int studcount=1;studcount<=studcountmax;studcount++)
   	{
   		cout<<ctime(&t)<<endl<<endl;
   		gotoxy(26,4);
   		cout<<"Student Term Evaluation Record"<<endl;
   		gotoxy(26,5);
   		cout<<"~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"<<endl<<endl;
   		cout<<"\t\tEnter the 1st term mark: - ";
   		cin>>term1;
         cout<<"\t\tEnter the 2nd term mark: - ";
         cin>>term2;

         studaverage = (term1 + term2)/2;
         classtotal = classtotal + studaverage;

   	   // redirect standard output to a file //
   		if (freopen("OPEN.txt", "a", stdout)== NULL)

      		fprintf(stderr, "error redirecting stdout\n");

   		//this output will go to a file //
         {
         printf("Student ",studcount,"%f",studaverage);
         cout<<endl;
         }

         // close the standard output stream //
         fclose(stdout);
         clrscr();
     	}



   getch();

   return 0;
}

I want it to look like this in the txt file;

student 1 63.00%
student 2 78.00%

etc. but its not working properly.

what are those braces supposed to be enclosing? there's no loop or conditional starting there