g++ and make

[Daniel]

This might be a little bit off group but I wanted to learn to work with
make in linux so I write this makefile

main: main.cpp ./EscribeHolaMundo.cpp ./EscribeHolaMundo.H
g++ -I. main.cpp ./EscribeHolaMundo.cpp -o main

with

EscribeHolaMundo.cpp

#include <iostream>

void EscribeHolaMundo() {
cout << "Hola Mundo";
}

and

main.cpp

#include <EscribeHolaMundo.H>

int main(int argc, char *argv[]) {
EscribeHolaMundo();
}

now, with this, make doesn't recognize cout

../EscribeHolaMundo.cpp:4: error: `cout' undeclared (first use this
function)

but if I use the old c sintaxis with <iostream.h>, then g++ produces
its warning about the deprecated headers but works. Can somebody tell
me why it doesn't work with <iostream>?

Daniel

 

[Daniel]

This has nothing to do with makefiles (neither does this
group). You forgot to write

using namespace std;

after your #include<iostream>

The issue is that the new header files (ones without the .h)
declare symbols in the std namespace, whereas the old ones
(with the .h), which you should avoid, declare the symbols
globally.

HTH,
- J.

Of course, very stupid of me, thanks

Daniel

 

[Jacek Dziedzic]

This might be a little bit off group but I wanted to learn to work with
make in linux so I write this makefile

main: main.cpp ./EscribeHolaMundo.cpp ./EscribeHolaMundo.H
g++ -I. main.cpp ./EscribeHolaMundo.cpp -o main

with

EscribeHolaMundo.cpp

#include <iostream>

void EscribeHolaMundo() {
cout << "Hola Mundo";
}

and

main.cpp

#include <EscribeHolaMundo.H>

int main(int argc, char *argv[]) {
EscribeHolaMundo();
}

now, with this, make doesn't recognize cout

./EscribeHolaMundo.cpp:4: error: `cout' undeclared (first use this
function)

but if I use the old c sintaxis with <iostream.h>, then g++ produces
its warning about the deprecated headers but works. Can somebody tell
me why it doesn't work with <iostream>?

Daniel

This has nothing to do with makefiles (neither does this
group). You forgot to write

using namespace std;

after your #include<iostream>

The issue is that the new header files (ones without the .h)
declare symbols in the std namespace, whereas the old ones
(with the .h), which you should avoid, declare the symbols
globally.

HTH,
- J.