macOS problem with c++ file I/O on xcode

[mark5907]

I just start learning c++ programming and I am using xcode on my mac.


I have a question about file I/O(maybe a very silly one)
I tried to open Scopy.cpp and copy the content to another file Scopy2.cpp.
I put both of the file in the directory same as the project.
#include <string>
#include <fstream>
using namespace std;

int main() {
ifstream in("Scopy.cpp"); // Open for reading
ofstream out("Scopy2.cpp"); // Open for writing
string s;
while(getline(in, s)) // Discards newline char
out << s << "\n"; // ... must add it back
}


but nothing happened after I run the code.


Please tell me how to do it in the right way?

 

[KnightWRX]

Maybe you should read a book about C++. You've managed to wrongly use every function and objects in that 5 lines of code.

Here's a good place to start, ifstream reference :

http://www.cplusplus.com/reference/iostream/ifstream/ifstream/

 

[mark5907]

thank you for you help, but I think we are not on the same page.

I copy the example from the book "thinking in c++ volume 1"

I tried the website, and use the following example from it.

#include <iostream>
#include <fstream>
using namespace std;

int main () {

ifstream ifs ( "test.txt" , ifstream::in );

while (ifs.good())
cout << (char) ifs.get();
ifs.close();

return 0;
}


I made a file test.txt and type some random words in it. I put it in the working directory. but this is what I got after I run the code


Loading program into debugger…
Program loaded.
run
[Switching to process 3551]
Running…

Debugger stopped.
Program exited with status value:0.

 

[KnightWRX]

Works like a champ here :

$ cat test.cpp
#include <iostream>
#include <fstream>
using namespace std;

int main () {

ifstream ifs ( "test.txt" , ifstream::in );

while (ifs.good())
cout << (char) ifs.get();
ifs.close();

return 0;
}
$ cat test.txt
allo
allo
allo
allo
$ g++ -o test test.cpp
$ ./test
allo
allo
allo
allo

Are you sure your program is finding the test.txt file ?

 

[LtRammstein]

Make sure your test text file is in the project directory. If your file isn't in it, then you'll run into issues unless you put in the exact path.

 

[chown33]

The OP should read this other thread:
https://forums.macrumors.com/threads/796818/