returning a string

[Vector]

...

Alright this is much better! But i dont know the primary expression that is exepected on 27 before openInputFile.

int main()
{
    string MyFile, 
    sFile = "hello.cpp";
    
    cout << "Enter a file: ";
    cin >> MyFile ;
    
    fstream ReadFile( fstream openInputFile );  // declare the fp within main()
       
    
    if ( MyFile != sFile )    // file must be 'hello.cpp' to proceed
    {
    cout << "Error";
    exit(0);
    }
                         // if correct file is entered print the contents of it
            cout << ReadFile( fstream openInputFile ); 
                        
    
    system("pause");    // temporary! 
    return 0;
}

// done with main now we can start this function
fstream ReadFile( fstream openInputFile )
{ 
       string sLine;   
       while ( getline ( openInputFile, sLine ) )
         {
			if ( sLine.length() == 0 ) continue;  // to proceed
			
      		 for ( int chgLine = 0; chgLine < sLine.length(); chgLine++ )
	     	 {
                if ( sLine[chgLine] >= 97 && sLine[chgLine] <= 122 || sLine[chgLine] >= 65 && sLine[chgLine] <= 90  )
                {
                     cout << sLine[chgLine];
                }
                
             }
          }
}

[helios]

Line 9: that's not how you call a function: ReadFile(???);
There are things missing:
* What is openInputFile?
* Why does ReadFile() return an fstream?

If you have a function declared as
int f(int);
you don't call it like this:
int f(int 4);
You call it like this:
var=f(4);

Are you getting any other errors?

[Vector]

No other errors..

Are their tutorials for these things? I have yet to find any.

You call it like this:
var=f(4);

How would i use this?

[Bazzy]

Streams don't have copy constructors, so you have to pass them by reference.
As helios said you are calling the function in a wrong way.
Here some tutorials on using functions:
http://www.cplusplus.com/doc/tutorial/functions.html
http://www.cplusplus.com/doc/tutorial/functions2.html
http://www.cprogramming.com/tutorial/print/lesson4.html

[Vector]

#include <fstream>
#include <string>
#include <iostream>

using namespace std;

ifstream ReadFile( ifstream& openInputFile, string& sLine, int& chgLine )
{ 
       
       while ( getline ( openInputFile, sLine ) )
       {
			if ( sLine.length() == 0 ) continue;  // to proceed
			
             for ( chgLine = 0; chgLine < sLine.length(); chgLine++ )
	     	 {
                if ( sLine[chgLine] >= 97 && sLine[chgLine] <= 122 || sLine[chgLine] >= 65 && sLine[chgLine] <= 90  )
                {
                     cout << sLine[chgLine];
                }
                
             }
        }
}

int main()
{
    int chgLine;
    string MyFile, sLine, 
    sFile = "hello.cpp";
    
    cout << "Enter a file: ";
    cin >> MyFile ;
    
    ifstream openInputFile;
      
    
    if ( MyFile != sFile )    // file must be 'hello.cpp' to proceed
    {
       cout << "Error";
       exit(0);
    }
                         // if correct file is entered print the contents of it
   
        ReadFile( openInputFile, sLine, chgLine );
    
    system("pause");
    return 0;
}

[Bazzy]

Declaration:ifstream ReadFile( ifstream& openInputFile, string& sLine, int chgLine ) (three arguments: openInputFile, sLine, chgLine)
Call: ReadFile( open ); (one argument: open)
You have to pass the same number of arguments and of the same type used on the declaration. (If you want it, you can declare an argument to be optional)

[Vector]

It complies now but im getting some oct code. My Plan was to use the ReadFile func to shorten the length of main.

I dont like the fact that i have to re-declare my paramters but evidently thats just the way life is.

Anyways, I think im going to do this step by step, one FP that does its own individual task, i.e. openFile, readFile, do something with the file.

ifstream openInputFile()
{
        string MyFile,
        ifstream inFile;
        
        inFile.open( MyFile.c_str(), ios::in );
        // return a pointer is what im looking for.    
}

int main()
{
   // prompt user for the file
   // validate
   // use openInputFile to find if userInput matchs the file
}

Its so simple. Im so ashamed.

[helios]

Keep in mind that local objects go out of scope when the function that created them returns, so if you return a pointer to one and try to use that pointer, you'll cause a segmentation fault.
Example:

int *f(){
	int a;
	return &a; //Error!
}