Print To Error Stream C
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Print To Stderr C++
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Fprintf Stderr Example
favorite 3 According to the docs, fprintf can fail and will return a negative number on failure. There are clearly many situations where it would be useful to check this value. However, I usually use fprintf to print error messages to stderr. My code will usually look something like this: rc = foo(); if(rc) { fprintf(stderr, "An error occured\n"); //Sometimes stuff will need to be cleaned up here return stderr vs stdout 1; } In these cases, is it still possible for fprintf to fail? If so, is there anything that can be done to display the error message somehow or is there is a more reliable alternative to fprintf? If not, is there any need to check fprintf when it is used in this way? c share|improve this question asked Jan 31 '11 at 0:18 Rupert Madden-Abbott 6,003104055 add a comment| 5 Answers 5 active oldest votes up vote 11 down vote accepted The C standard says that the file streams stdin, stdout, and stderr shall be connected somewhere, but they don't specify where, of course. It is perfectly feasible to run a program with them redirected: some_program_of_yours >/dev/null 2>&1 &- 2>&-
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Print To Stderr Bash
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“standard” input and output channels that have been established for http://www.gnu.org/s/libc/manual/html_node/Standard-Streams.html the process. These streams are declared in the header file stdio.h. Variable: FILE * stdin The standard input stream, which is the normal https://www.rosettacode.org/wiki/Hello_world/Standard_error source of input for the program. Variable: FILE * stdout The standard output stream, which is used for normal output from the program. print to Variable: FILE * stderr The standard error stream, which is used for error messages and diagnostics issued by the program. On GNU systems, you can specify what files or processes correspond to these streams using the pipe and redirection facilities provided by the shell. (The primitives print to stderr shells use to implement these facilities are described in File System Interface.) Most other operating systems provide similar mechanisms, but the details of how to use them can vary. In the GNU C Library, stdin, stdout, and stderr are normal variables which you can set just like any others. For example, to redirect the standard output to a file, you could do: fclose (stdout); stdout = fopen ("standard-output-file", "w"); Note however, that in other systems stdin, stdout, and stderr are macros that you cannot assign to in the normal way. But you can use freopen to get the effect of closing one and reopening it. See Opening Streams. The three streams stdin, stdout, and stderr are not unoriented at program start (see Streams and I18N). Next: Opening Streams, Previous: Streams, Up: I/O on Streams [Contents][Index]
< Hello worldJump to:navigation, search Hello world/Standard error You are encouraged to solve this task according to the task description, using any language you may know. Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to "standard error". This separation can be used to redirect error messages to a different place than normal messages. Task Show how to print a message to standard error by printing Goodbye, World! on that stream. Contents 1 4DOS Batch 2 Ada 3 Aime 4 ALGOL 68 5 Argile 6 ATS 7 AutoHotkey 8 AutoIt 9 AWK 10 BASIC 10.1 ZX Spectrum Basic 11 Batch File 12 BBC BASIC 13 C 14 C# 15 C++ 16 Clojure 17 CMake 18 COBOL 19 CoffeeScript 20 Common Lisp 21 D 21.1 Alternative Version 22 Déjà Vu 23 Delphi 24 Dylan.NET 25 E 26 Elixir 27 Emacs Lisp 28 Erlang 29 Euphoria 30 F# 31 Factor 32 Fantom 33 Forth 34 Fortran 35 FreeBASIC 36 Frink 37 Go 38 Groovy 39 Haskell 40 Icon and Unicon 41 J 42 Java 43 JavaScript 44 jq 45 Julia 46 Lasso 47 Lingo 48 Logtalk 49 Lua 50 m4 51 Mathematica / Wolfram Language 52 MATLAB / Octave 53 Mercury 54 Metafont 55 ML/I 56 Modula-2 57 Modula-3 58 Nemerle 59 NetRexx 60 Nim 61 Oberon-2 62 Objective-C 63 OCaml 64 Octave 65 Oforth 66 ooRexx 67 Oz 68 PARI/GP 69 Pascal 70 Perl 71 Perl 6 72 Phix 73 PHP 74 PicoLisp 75 PL/I 76 PostScript 77 PowerBASIC 78 PowerShell 79 PureBasic 80 Python 81 R 82 Ra 83 Racket 84 Retro 85 REXX 85.1 version 1 85.2 version 2 85.3 version 3 86 Ring 87 Ruby 88 Run BASIC 89 Rust 90 S-lang 91 Salmon 92 Sather 93 Scala 93.1 Ad hoc REPL solution 93.2 Via Java runtime 93.3 Via Scala Console API 93.4 Short term deviation to err 93.5 Long term deviation to err 94