function to read a stream


N

nvangogh

Hi, I am stuck on exercise 8.1 (at section 8.1.2) p314 of C++ Primer 5th
Edition (Lippman, Lajoie, Moo). The exercise says:

"Write a function that takes and returns an istream&. The function
should read the stream until it hits end-of-file. The function should
print what it reads to the standard output. Reset the stream so that it
is valid before returning the stream."

Suppose I have declared:

istream& read(istream&);

How do I go about defining this function?
Thanks in advance.
 
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V

Victor Bazarov

Hi, I am stuck on exercise 8.1 (at section 8.1.2) p314 of C++ Primer 5th
Edition (Lippman, Lajoie, Moo). The exercise says:

"Write a function that takes and returns an istream&. The function
should read the stream until it hits end-of-file. The function should
print what it reads to the standard output. Reset the stream so that it
is valid before returning the stream."

Suppose I have declared:

istream& read(istream&);

How do I go about defining this function?

Start by giving the name to the argument, opening the body of the
function (a curly brace should do), and returning the argument passed
in, then closing the body (another curly brace).

Do you know how to read the stream? The simplest is reading one char at
a time. Do you know how to check the stream's "end-of-file" condition?
Do you know how to define a loop *until* some condition is met (hint:
use 'while')?

V
 
N

nvangogh

Start by giving the name to the argument, opening the body of the
function (a curly brace should do), and returning the argument passed
in, then closing the body (another curly brace).

Do you know how to read the stream? The simplest is reading one char at
a time. Do you know how to check the stream's "end-of-file" condition?
Do you know how to define a loop *until* some condition is met (hint:
use 'while')?

V
could you show the code?
 
N

nvangogh

Is this a correct solution?


#include <iostream>
#include <string>
istream& read(istream& in)
{
std::string word;
while(in >> word)
{
std::cout << word;
}

// reset stream so it's in a valid state
in.clear();
return in;
}
 
N

nvangogh

If I try to compile this I get an error:

#include <iostream>
#include <string>

// declaration
istream& read(istream&);

// definition
istream& read(istream& in)
{
std::string word;
while(in >> word)
{
std::cout << word << endl;
}

// reset stream so it's in a valid state
in.clear();
return in;
}

int main()
{
std::cout << "Input some txt";
read(std::cin);
return 0;
}

------------------------
 
N

nvangogh

If I try to compile this I get an error:

#include <iostream>
#include <string>

// declaration
istream& read(istream&);

// definition
istream& read(istream& in)
{
std::string word;
while(in >> word)
{
std::cout << word << endl;
}

// reset stream so it's in a valid state
in.clear();
return in;
}

int main()
{
std::cout << "Input some txt";
read(std::cin);
return 0;
}

------------------------
Its ok I've done it
 
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