How to call other program?

Xiangbuilder · 09-11-2003, 07:47 AM

This is the source code in <<Thinking in C++>> volume one, chapter 2, Making and using object.

Code:

//: C02:CallHello.cpp
// Call another program
#include <cstdlib> // Declare "system()"
using namespace std;

int main() {
  system("Hello");
} ///:~

I can successfully compile Hello.cpp and run it, but I don't know how to compile CallHello.cpp and run it successfully.

Thank you.

kev82 · 09-11-2003, 08:09 AM

how about:

g++ -o CallHello CallHello.cpp
./CallHello

i assume if you compiled Hello.cpp then you did this already which means you getting some sort of error, if you tell us what it is we might be able to help

Xiangbuilder · 09-11-2003, 08:53 AM

Thank you.
[root@localhost first]# g++ CallHello.cpp -o CallHello
(No error when compile.)
[root@localhost first]# ./CallHello
sh: line 1: Hello: command not found
(Such error occur when the program is run.)

Strike · 09-11-2003, 09:07 AM

Then you are missing the "Hello" program that you are trying to call.

kev82 · 09-11-2003, 09:12 AM

Quote:

Originally posted by Strike
Then you are missing the "Hello" program that you are trying to call.

possibly but he says he's compiled that and its ok.

Xiangbuilder: try system("./Hello"); in CallHello.cpp and see what happens. also do you really need root privilages to do this??

Xiangbuilder · 09-11-2003, 10:31 AM

I tried system("./Hello"); in CallHello.cpp and it is ok, then.
I wonder if you leave system("Hello") instead of system("./Hello") in CallHello.cpp, and and you can successfully compile Hello.cpp and run it,
can you successfully compile CallHello.cpp and run it in your machine?
I ask the question because the words in the book is system("Hello") rather than system("./Hello").
I offten see some command such as "xxx" in web, in fact, to run it, we must type ./xxx instead of xxx.
Thank you.

captainstorm · 09-11-2003, 10:47 AM

<<Thinking in C++>> is not O.S specific.
But "./XXX" to excecute the file is the linux rule.

I think...

Nylex · 09-11-2003, 11:14 AM

Quote:

Originally posted by captainstorm
<<Thinking in C++>> is not O.S specific.
But "./XXX" to excecute the file is the linux rule.

I think...

That's only if . (the current directory) isn't in your path variable. If it is, you can simply type the name of the executable, eg CallHello.

jinksys · 09-11-2003, 12:02 PM

As previously noted, linux uses ./ to specify an executable in the current directory. I have no idea what OS the author of Thinking in C++ was using when writing the book, but it could have been windows or one of the versions of Unix that does not require ./
I have no idea what versions of Unix those would be, but Ive heard they exist.

kev82 · 09-11-2003, 12:09 PM

by jinksys
I have no idea what OS the author of Thinking in C++ was using when writing the book, but it could have been windows

the author, Bruce Eckel was writing in windows as volume two of his book comes in MSWord format or at least it did when i read it.

by jinksys
I have no idea what versions of Unix those would be, but Ive heard they exist.

any version of unix where someone cares to type

Code:

export PATH=$PATH:.

assuming bash, i dont know my other shells very well.

jinksys · 09-11-2003, 12:41 PM

Thanks for clearing that up.

Xiangbuilder · 09-11-2003, 09:13 PM

Thank you.