stdout and stderr how to proceed

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1.00/5 (1 vote)

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Let suppose I am make a program of adding 2 numbers and giving input from the command line
as
c://>program_name 12 13

How can i proceed so that output of my program must go to stdout and error messages must go to stderr?

int main(int argc, char *argv[])
{    
                   
      int i=argv[1];
      string j=argv[2];
      cout<<i+j;
      getch();
      return 0;
}

Posted 28-Aug-11 16:20pm

Trick7

Updated 28-Aug-11 18:16pm

Albert Holguin

v3

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Simon Bang Terkildsen · Answer 1 · 2011-08-28T16:39:00

Solution 1

cin reads from stdin
cout writes to stdout
cerr writes to strerr

C++

string input;
cin >> input; // Read from stdin
cout << "Write to stdout";
cerr << "Write to stderr";

Is stdout and stderr used in c++?
Yes, like I said cout and cerr writes to those.

by using fprintf() or stuff like that by taking streams?
Ifyou want to use fprintf then you just pass the stream you want to write to as the first parameter:

C++

#include <stdio.h>
fprintf(stdout, "Writing to stdout");

FILE* stdout, stderr, stdin are defined in stdio.h

Posted 28-Aug-11 16:39pm

Simon Bang Terkildsen

Updated 29-Aug-11 15:14pm

v5

Comments

Trick7 28-Aug-11 22:47pm

I got u but can u please write some code so that i can have some better understanding

Simon Bang Terkildsen 28-Aug-11 22:50pm

well you already did that yourself in the code you posted, but I've updated the answer to include sample code.

Trick7 28-Aug-11 22:54pm

Is stdout and stderr used in c++????
by using fprintf() or stuff like that by taking streams???

Simon Bang Terkildsen 28-Aug-11 23:02pm

updated the answer

Trick7 28-Aug-11 23:09pm

c://>program_name 12 13

//header files included....
int main(int argc, char *argv[])
{
FILE* stdout, stderr;
int i=argv[1];
string j=argv[2];
int p=i+j;
int fprintf(stdout, "%d\n", p);
getch();
return 0;
}

but error is coming........
help........

Simon Bang Terkildsen 28-Aug-11 23:44pm

Remove FILE* stdout, stderr; as I said these are defined in stdio.h

Simon Bang Terkildsen 28-Aug-11 23:49pm

argv[1] is char* not int
int p=i+j; j is a string
Almost every line is wrong and wont compile.
Take my advice forget everything you've learned and start over with a book for beginners and you might want to start out with C# or Java instead of c++.
I don't say this to be malicious, but to help you.

Trick7 28-Aug-11 23:13pm

error above:
declartion of ' iob' as a array of reference....
Help;;

Albert Holguin 29-Aug-11 14:28pm

+5 for effort... whew! :D

Simon Bang Terkildsen 29-Aug-11 15:07pm

Thank you XD