Hi Julian,
I am currently at work and haven't Dev-C++ installed, so I canot test your
program.
I noticed that you do not test the outcome of the open for either of your
files. This would be a good first step.
E.g. Extract from Bjarne Stroustrup, p.638
(note: your example may vary slightly for it to work)
ifstream from(file1);
ofstream to (file2);
if (!from) ...;
if (!to) ...;
If I have time I will download Dev-C++ later to try it out but I am very
busy right now.
Hope my little contribution helps,
Michael
>From: Julian Etienne <j_e...@ya...>
>Reply-To: dev...@li...
>To: dev...@li...
>Subject: [Dev-C++] HELP---Read/Write Files in Dev C++
>Date: Mon, 24 Sep 2001 14:27:42 -0700 (PDT)
>
>I have a program that complies and runs in both
>Microsoft C++ 6.0, and my schools Dec Unix C++
>complier. I opened a new project in Dev C++ make it a
>console application. I added these three files to my
>project pwrpro.h, pwr.cpp, runpwr.cpp The program
>compiles with no errors. The problem is that this
>program should read data from a file and the then
>write a new file, with calculations in it. It writes a
>blank file. I am wondering if I am missing something
>for it to work correctly in this IDE. When i do not
>put my file in.data in the directory it correctly
>prints "the file is not found" in the output file.
>
>ANY HELP WILL BE GREATLY APPRECIATED!!!!
>
>//----------
>// Specification File (pwrpro.h)
>// This module provides exponentiation functions.
>//----------
>
>int PowerOfInt ( int someInt, int exp );
>// PRE: Assign int (someInt) and exp > 0
>// POST: Firstnum raised to the power "expon1"
>//(NOTE: Large exponents may produce overflow)
>
>float PowerOfFloat ( float someFloat, int exp );
>// PRE: Assign float (someFloat) and assigned some exp
> > 0
>// POST: someFloat raised to the power "exp"
>//(NOTE: Large exponents may produce overflow)
>
>bool NonZeroInt (int exp);
>//PRE: Take infile exp
>//POST: make sure exp > 0
>
>-----------------------------------------------
>-----------------------------------------------
>-----------------------------------------------
>
>//----------
>// Specification File (pwr.cxx)
>// This module provides exponentiation functions.
>//----------
>#include <iomanip.h>
>#include "pwrpro.h"
>
>int PowerOfInt ( int someInt, int exp )
>//...........
>// PRE: Assign int (someInt) and exp > 0
>// POST: Firstnum raised to the power "expon1"
>//(NOTE: Large exponents may produce overflow)
>//...........
>{
>
>int i;
>int partialVal = 1;
>
>for ( i = 1; i <= exp; i++)
>partialVal *= someInt;
>return partialVal;
>
>}
>
>float PowerOfFloat (float someFloat, int exp )
>//...........
>// PRE: Assign float (someFloat) and assigned some exp
> > 0
>// POST: someFloat raised to the power "exp"
>//(NOTE: Large exponents may produce overflow)
>//...........
>{
>int i;
>float partialVal = 1.0;
>
>for ( i = 1; i <= exp; i++)
>partialVal *= someFloat;
>return partialVal;
>
>}
>
>bool NonZeroInt (int exp)
>//..........
>//PRE: Take infile exp
>//POST: make sure exp > 0
>//..........
>{
>bool value;
>
>if (exp <= 0) value = false;
>else
>value = true;
>return value;
>}
>
>-------------------------------------------------
>-------------------------------------------------
>-------------------------------------------------
>
>//*************************************************************************
>
>
>//PURPOSE
>// runpwr.cxx)
>// This program reads IntNum, IntExp, FloatNum,
>FloatExp from an input file and calculates
>// IntNum^Int Exp and Float Num^ Float Exp.
>// Note X^n denotes X raised to the nth power.
>//*************************************************************************
>
>
>#include <fstream.h>
>#include <iomanip.h>
>#include "pwrpro.h"
>
>int main()
>{
>ifstream inFile;
>ofstream outFile;
>
>inFile.open("in.data", ios::nocreate );
>outFile.open("out.data");
>
>if (! inFile)
>{
>outFile<<" ERROR: Unable to locate file named
>'in.data' "<<endl;
>return 0;
>}
>
>int IntExp, FloatExp, IntNum;
>float FloatNum;
>
>inFile >> IntNum >> IntExp >> FloatNum >> FloatExp;
>
>while (! inFile.eof() )
>{
>
>if (NonZeroInt (IntExp)== false)
>outFile <<"This Function accepts only "
><<"postive integer exponents!"
><<" Your exponent is zero or negative.
>
>";
>else
>{
>
>outFile <<IntNum << "^"<< IntExp << " = " << setw (10)
>
><< PowerOfInt(IntNum,IntExp) <<endl;
>
>}
>
>
>if (NonZeroInt (FloatExp)== false)
>outFile <<"This Function accepts only "
><<"postive integer exponents!"
><<" Your exponent is zero or negative.
>
>";
>else
>{
>
>outFile <<FloatNum << "^"<<FloatExp << " = " << setw
>(10)
><<setiosflags(ios::fixed) << setprecision
>(2)<<PowerOfFloat(FloatNum, FloatExp)
><<endl <<endl;
>
>}
>
>inFile >> IntNum >> IntExp >> FloatNum >> FloatExp;
>}
>
>inFile.close();
>outFile.close();
>return 0;
>}
>
>
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