C++ iostream

[NTHQ]

I hadn't done C++ in a few years so I decided to take out my old book that I learned from to refresh myself. Back then I used Visual C++ to write my programs. When I started programming in Java I used Eclipse and got used to it. So I installed it in Ubuntu and also got CDT to do my C++ programming.
I'm having trouble with these two programs that came from my book.

#include <iostream>
using namespace std;
int main()
{
int ch;
int count = 0;
while((ch = cin.get()) != EOF)
{
cout << char(ch);
count++;
}
cout << "\nCharacter count = " << count << "\n";
return 0;
}

#include <iostream>
using namespace std;
const int Size = 10;
int main()
{
int grades[Size];
cout << "\nEnter student grades.";
cout << "\nProgram terminates beyond " << Size << " entries ";
cout << "or a -ve entry\n";
int num;
cin >> num;
int i = 0;
while(i < Size && num >= 0)
{
grades[i++] = num;
if(i < Size)
cin >> num;
}
if(i == 0)
cout << "\nNo grades entered!\n";
else
{
fflush(stdin);
cout << "\nEnter your grade: ";
int grade;
cin >> grade;
int count = 0;
for(int j = 0;j < i;j++)
if(grades[j] > grade)
count++;
cout << count << " students have a higher grade than you\n";
}
return 0;
}
This is what the console gives when I try to build each program respectively.


**** Build of configuration Debug for project PROG30 ****

make all
Building file: ../prog30.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"prog30.d" -MT"prog30.d" -o"prog30.o" "../prog30.cpp"
../prog30.cpp: In function ‘int main()’:
../prog30.cpp:7: error: ‘EOF’ was not declared in this scope
make: *** [prog30.o] Error 1


**** Build of configuration Debug for project PROG33 ****

make all
Building file: ../prog33.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"prog33.d" -MT"prog33.d" -o"prog33.o" "../prog33.cpp"
../prog33.cpp: In function ‘int main()’:
../prog33.cpp:23: error: ‘stdin’ was not declared in this scope
../prog33.cpp:23: error: ‘fflush’ was not declared in this scope
make: *** [prog33.o] Error 1
From what I know, EOF, stdin, and fflush should all be declared inside iostream no? So why does it tell me that they are not?

[unknownPoster]

I compiled your first program manually via:

g++ -Wall file.cpp -o run

Everything compiled and ran successfully that way.

I believe there may be an issue with your build configurations. I only use Eclipse for Java development so I'm not exactly sure how to assist you with Eclipse and C++.

[Brandon Williams]

EOF, stdin, and fflush are all part of the C stdio library. You may need to include <cstdio> to get those. It's generally better to avoid mixing iostream and stdio, though. Just use functionality that's in iostream instead. Look here (http://www.cplusplus.com/reference/iostream/istream/get/) for an alternate example of how to use istream::get for character based input. And just use cin.flush() to flush stdin.

[NTHQ]

This is what I wrote in my makefile.

all:
g++ prog30.cpp -o prog30
I am not very familiar with makefiles since I didn't have to write them in Visual C++. Could there be something wrong there?

[NTHQ]

EOF, stdin, and fflush are all part of the C stdio library. You may need to include <cstdio> to get those. It's generally better to avoid mixing iostream and stdio, though. Just use functionality that's in iostream instead. Look here (http://www.cplusplus.com/reference/iostream/istream/get/) for an alternate example of how to use istream::get for character based input. And just use cin.flush() to flush stdin.
I included cstdio and and it works now thanks a lot. :)

[dwhitney67]

EOF is indeed a C thingy.

In C++, the while-conditional should be something similar to:


while((ch = cin.get()) && !cin.eof())
{
...
}



P.S. It should be noted that this also would have worked:


char ch;
int count = 0;
while(cin.get(ch))
{
...
}