Kursusindhold
C++ Introduction
C++ Introduction
Forståelse af Standardbiblioteket og Filer i C++
Standardbiblioteker fungerer som lagre af forudskrevet, genanvendelig kode, der forenkler almindelige opgaver. De sparer udviklere tid og kræfter ved at tilbyde veltestede, standardiserede værktøjer til at bygge software.
Grundlæggende er de bare filer, som du kan inkludere i dit projekt. Nogle af dem dækker essentielle opgaver som at udskrive information eller arbejde med tekst, mens andre er mere specifikke og dækker områder som netværk. Her er kildekoden for nogle af dem:
iostream
iomanip
string
// Standard iostream objects -*- C++ -*- // Copyright (C) 1997, 1998, 1999, 2001, 2002, 2005, 2008, 2009, 2010 // Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file include/iostream * This is a Standard C++ Library header. */ // // ISO C++ 14882: 27.3 Standard iostream objects // #ifndef _GLIBCXX_IOSTREAM #define _GLIBCXX_IOSTREAM 1 #pragma GCC system_header #include <bits/c++config.h> #include <ostream> #include <istream> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION /** * @name Standard Stream Objects * * The <iostream> header declares the eight <em>standard stream * objects</em>. For other declarations, see * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch24.html * and the @link iosfwd I/O forward declarations @endlink * * They are required by default to cooperate with the global C * library's @c FILE streams, and to be available during program * startup and termination. For more information, see the HOWTO * linked to above. */ //@{ extern istream cin; /// Linked to standard input extern ostream cout; /// Linked to standard output extern ostream cerr; /// Linked to standard error (unbuffered) extern ostream clog; /// Linked to standard error (buffered) #ifdef _GLIBCXX_USE_WCHAR_T extern wistream wcin; /// Linked to standard input extern wostream wcout; /// Linked to standard output extern wostream wcerr; /// Linked to standard error (unbuffered) extern wostream wclog; /// Linked to standard error (buffered) #endif //@} // For construction of filebuffers for cout, cin, cerr, clog et. al. static ios_base::Init __ioinit; _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif /* _GLIBCXX_IOSTREAM */
Hvorfor bruge standardbiblioteker og filer
At skrive kode med et bibliotek er som at skrive en bog med en ordbog. Vi kan nemt erstatte en sætning med kun ét ord uden at miste hovedbetydningen
Du kan omskrive dette ved hjælp af allerede eksisterende termer fra en ordbog. Ligesom at bruge et eksisterende bibliotek, kan du reducere hundredevis af linjer kode til blot en enkelt ved hjælp af et bibliotek.
Tak for dine kommentarer!
