Strange output in loop

[riva]

#include <iostream>
using namespace std;

int main(void)
{
int i=0;
while(char c = cin.get() != EOF) {
i++;
cout << i << c << endl;
}
}

I am a C programmer and I am learning C++ from Thinking in C++.
The problems with the above code are:
1) i is incremented twice and the output is printed twice.
2) c is not printed.

[Joe Greer]

riva <ra*********@gmail.comwrote in news:1194284825.342443.93040
@e34g2000pro.googlegroups.com:

#include <iostream>
using namespace std;

int main(void)
{
int i=0;
while(char c = cin.get() != EOF) {
i++;
cout << i << c << endl;
}
}

Well, the problem is that you are assigning c the value of the comparison
between cin.get() and EOF. I am sure this isn't what you want. Try:

#include <iostream>
using namespace std;

int main()
{
int i=0;
char c;

while ((c = cin.get()) != EOF) {
i++;
cout << i << c << endl;
}
}

joe

[Ioannis Gyftos]

On Nov 6, 3:23 pm, riva <[e-mail]:

#include <iostream>
using namespace std;

int main(void)
{
int i=0;
while(char c = cin.get() != EOF) {
i++;
cout << i << c << endl;
}

}

I am a C programmer and I am learning C++ from Thinking in C++.
The problems with the above code are:
1) i is incremented twice and the output is printed twice.
2) c is not printed.

And your question is?

You probably mean something like
while(
(c = std::cin.get()) != EOF
) { ... }

Without the parentheses, you compare std::cin.get() with EOF, and
assign the result of the comparison to c. Then, c will contain some
sort of boolean representation, which is usually not printable (\0,
\1, or whatever).

[Justin Spahr-Summers]

On Nov 6, 7:36 am, Joe Greer <[e-mail]:

Well, the problem is that you are assigning c the value of the comparison
between cin.get() and EOF. I am sure this isn't what you want. Try:

. . .
char c;

while ((c = cin.get()) != EOF) {
. . .

If 'char' is unsigned on a given implementation, this comparison could
lead to some odd behavior, as EOF is guaranteed to be negative (which
is why many I/O functions that handle single characters take and
return values of type int).