function to read a stream

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.

 

On 5/13/2014 12:13 PM, nvangogh wrote:
> 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
--
I do not respond to top-posted replies, please don't ask

 

On 13/05/14 17:19, Victor Bazarov wrote:
> On 5/13/2014 12:13 PM, nvangogh wrote:
>> 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
could you show the code?

 

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;
}

 

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;
}

------------------------
> g++ -std=c++11 -o exercise8.1 exercise8.1.cpp
> exercise8.1.cpp:7:1: error: ‘istream’ does not name a type
> exercise8.1.cpp:10:1: error: ‘istream’ does not name a type
> exercise8.1.cpp: In function ‘int main()’:
> exercise8.1.cpp:26:16: error: ‘read’ was not declared in this scope
-------------------------

Can someone please show me how to do this exercise?

 

On 13/05/14 18:42, nvangogh wrote:
> 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;
> }
>
> ------------------------
>> g++ -std=c++11 -o exercise8.1 exercise8.1.cpp
>> exercise8.1.cpp:7:1: error: ‘istream’ does not name a type
>> exercise8.1.cpp:10:1: error: ‘istream’ does not name a type
>> exercise8.1.cpp: In function ‘int main()’:
>> exercise8.1.cpp:26:16: error: ‘read’ was not declared in this scope
> -------------------------
>
> Can someone please show me how to do this exercise?
>
>
Its ok I've done it

 

On 13/05/14 18:31, James Moe wrote:
> On 05/13/2014 10:28 AM, nvangogh wrote:
>>> 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')?
>>>>
>> could you show the code?
>>
> How did you get to exercise 8.1 without knowing any of the above?
>
I know its a simple exercise, which I have solved now.