urls and filehandles

[pktcperlc++java]

firstly, filehandles

When a file contains text, for example, "hello, person"

an ofstream being used like this: ofstream>>variable would only read "hello,"

my thinking is that a loop like this:

while(variable!=NULL){

        ofstream>>variable;

}//end while

woudl read in the entire file

could someone cofirm that, or give me a different way to read in the whole file?

second, how do I get the html code from a webpage?

thanx

[elad]

The end of file is indicated by an EOF char, not NULL, which is a gauranteed location in memory, or a null char, which isn't the same as NULL. When the input stream finds the EOF char it will cause the stream to fail, and set the EOF bit. Therefore, the following syntax is commonly use to read in file data.

while(inputStreamName >> variableName)
{
   //do something with variableName other than overwriting it each time through loop
}
 
//determine why stream failed
if(inputStreamName.eof())
  //eof() evaluates to true if EOF bit is flipped
  cout << "file read in successfully" << endl;
else
  cout << "error reading in file" << endl;

[pktcperlc++java]

so...how do I concatenate the input?

would this work?:

while(! inputStreamName.eof()){

          inputStreamName>>temp;

          variable+=temp;

}//end while

[pablo615]

so...how do I concatenate the input?

would this work?:

while(! inputStreamName.eof()){

          inputStreamName>>temp;

          variable+=temp;

}//end while

That really depends on what you are reading from the file. Concatenating strings like that requires you to use a string object supporting the += operator. If its all numerical data, then += will give you the sum, so on and so forth.

There is no easy "do it this way all the time answer". Just make sure to save off what was read during each iteration so its not overwritten in the next iteration.

PK

[pktcperlc++java]

I should have been clearer

I meant to ask if the evaluation in the while loop was valid

[jlou]

Yes, it is valid. No, it will not work as you expect. Read the FAQ and do as elad suggested or your loop will go one too many times.

In addition, by using >> you are ignoring whitespace, and so when you add on the data to the variable then the whitespace is missing. There are many solutions to this, including reading the input without skipping whitespace, adding the whitespace back in if you know what it is, reading in the data from the file a character at a time, and using getline to read a line at a time.

[Junior89]

Do you mean displaying file contents? If you do you can do this:

ofstream fin("FILENAME");
char ch;
while(fin.get(ch))
{
     cout<<ch;
}
fin.close();

i think that's right...

[pktcperlc++java]

so, modified, would this work?

ofstream fin("FILENAME");
char ch;
while(fin.get(ch)){
storageString+=ch;
}//end while
fin.close();

[Junior89]

are you trying to get the contents of the file written into a string? I had the same question not too long ago and nobody gave me a simple solution so i used this and it worked:

...
ifstream fin("filename");
char ch;
char newstring[100];
int x;
x=0;
while(fin.get(ch))
{
     cout<<ch;
     newstring[x]=ch;
     x++;
}
...

i think that's right (im not at home right now so i cant check) but it worked for me.

[pktcperlc++java]

would this work? maybe?

#include <fstream>
#include <string>
#include <cstring>

using namespace std;
using std::string;

string readFile(string filename){

	string file;
	char *inread;
	
	ifstream inf (filename);
	
	while(inf.pos()<inf.eof()){
	
		inf>>inread[inf.pos];
		
	}//end while
	
	inf.close()
	
	for(int i=0;i<strlen(inread);i++){
	
		file+=inread[i];
		
	}//end for
	
	return file;
	
}//end readFile

I was assuming that ifstream had a function like pos that might say what the current position in the file might be

if it doesn't inf.pos() coudl be replaced with an incrementing value to mark position (starting at 0)

[pktcperlc++java]

for(int i=0;i<strlen(inread);i++){

file+=inread[i];

}//end for

sry, I forgot to add whitespace

after the

file+=inread[i]

there should be an if statement:

if(i!=strlen(inread)-1){

          file+=" ";

}//end if

[Salem]

> would this work? maybe?
Nope - inread is an uninitialised pointer.

[pktcperlc++java]

how bout this?

#include <fstream>
#include <string>
#include <vector>

using namespace std;
using std::string;

string readFile(string filename){

        string file;
        vector <char> inread;
        
        ifstream inf (filename);
        
        while(inf.pos()<inf.eof()){
        
                inf>>inread[inf.pos];
                
        }//end while
        
        inf.close()
        
        for(int i=0;i<inread.size();i++){
        
                file+=inread[i];
                
                if(i!=inread.size()-1){

                                file+=" ";

                }//end if

        }//end for
        
        return file;
        
}//end readFile

does pos() actually exit?

[andyhunter]

I was assuming that ifstream had a function like pos that might say what the current position in the file might be

Why do you need to assume anything? Look at the documentation, I know it may seem like a novel idea but it seems to work for everyone else.

[edit]

BTW this is the 3rd time you have made this post - I mean exact name and everything. Whats the deal?

[/edit]

[elad]

File pointers do exist, for example fseek() in C or seekp(), seekg(), tellg() and tellp())in C++. They wouldn't seem to the most efficient way to read a whole file, but if you knew exactly how much of a file you wanted to read, or if you wanted to start reading, stop reading, etc at a particular location in a file, then using them would make more sense. Such knowledge is more readily available if the file contents are perfectly ordered.

eof() returns a non-zero value if the end of file has been reached, and a zero value if the end of file hasn't been reached. What the non-zero value is is not indicated and I wouldn't recommend it be measured against as in

while(inf.pos()<inf.eof())