help with file output (fstream)....

[mark]

The problem with this code snippet is that only outputs the first word
in the file "test". The file has atleast one line with 4 words in it,
only one word is output. I have tried increasing the array size as
well, still only the first word is output ?
what is the error ?

file "test" contains "Line one here"
output ---> "line"
char str[20];
ifstream b_file("test");
b_file>>str;
cout<<str;
b_file.close();

 

[Sumit Rajan]

The problem with this code snippet is that only outputs the first word
in the file "test". The file has atleast one line with 4 words in it,
only one word is output. I have tried increasing the array size as
well, still only the first word is output ?
what is the error ?

file "test" contains "Line one here"
output ---> "line"
char str[20];
ifstream b_file("test");
b_file>>str;
cout<<str;
b_file.close();

That is what it is supposed to do. To handle it line-by-line, look up
std::getline(). For instance, the following would open a file and list it,
line-by-line:

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

int main()
{
std::ifstream is("somefile.txt");
std::string str;

while (std::getline(is, str)) {
std::cout << str << '\n';
}
}

Regards,
Sumit.

 

[SaltPeter]

The problem with this code snippet is that only outputs the first word
in the file "test". The file has atleast one line with 4 words in it,
only one word is output. I have tried increasing the array size as
well, still only the first word is output ?
what is the error ?

file "test" contains "Line one here"
output ---> "line"
char str[20];
ifstream b_file("test");
b_file>>str;
cout<<str;
b_file.close();

Post code that includes main() and shows what your include directives are at
the very least. Your ifstream is correctly reading the first "word" up to
the first space encountered in the stream. Try using std::getline instead:

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

int main()
{
std::ifstream ifs;
ifs.open("test", std::ios::in);
if(!ifs)
{
std::cout << "can't open input file stream\n";
return -1;
}

std::string s;
std::getline(ifs, s);

std::cout << s << std::endl;

ifs.close();

return 0;
}

 

[John Harrison]

The problem with this code snippet is that only outputs the first word
in the file "test". The file has atleast one line with 4 words in it,
only one word is output.

That's how it should work.

I have tried increasing the array size as

well, still only the first word is output ?

Arrays are passed to functions as pointers, so there is no way that any
function can know the size of an array passed to it. So increasing the size
of the array could not possibly make any difference.

This is an important point. You have declared a char array, but there is no
way at all using >> to stop the input if the char array isn't big enough.
Never, ever use >> on a char array. Most of the security flaws in Windows
are caused by this and similar errors. Ever heard of a buffer overrun? Well,
you just wrote one.

Fortunately C++ has a good solution, instead of using char arrays use a
string instead. When you input to a string it grows to the size that is
needed.

#include <string>

std::string word;
cin >> word; // no overrun possible

what is the error ?

RTFM I think. You seem to think that >> should read a line, but it doesn't,
it reads a word. Use getline instead.

john