Ubuntu日本語フォーラム

hellow201905 · 2019-05-15 16:21:02

Ubuntuのバージョン：Ubuntu 18.04.2 LTS

ソースファイル

コード:

hoge@hoge-VirtualBox:~/cTest$ cat hellow.cpp 
#include <iostream>
#include <stdio.h>

#define STR(var) #var
enum LogLevel
{
    ERROR,
    INFO,
    DEBUG
};

std::ostream& logStream(LogLevel level);
std::ostream& logStream(LogLevel level) {
    std::ostream stream = std::cout;
    if( level == ERROR ) {
        stream = std::cerr;
    }
    char szTime[90] = { 0 };
    time_t now = time(NULL);
    struct tm *pnow = localtime(&now);
    sprintf(szTime, "%04d/%02d/%02d %02d:%02d:%02d", pnow->tm_year + 1900, pnow->tm_mon + 1, pnow->tm_mday,
        pnow->tm_hour, pnow->tm_min, pnow->tm_sec);
    stream << szTime << "[" << STR(lebel) << "]";

    return stream;
}

int main() {
    logStream(INFO) << "Hellow." << std::endl;
    return 0;
}

コンパイル結果

コード:

hoge@hoge-VirtualBox:~/cTest$ c++ hellow.cpp 
hellow.cpp: In function ‘std::ostream& logStream(LogLevel)’:
hellow.cpp:14:29: error: ‘std::basic_ostream<_CharT, _Traits>::basic_ostream(const std::basic_ostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]’ is protected within this context
  std::ostream stream = std::cout;
                             ^~~~
In file included from /usr/include/c++/7/iostream:39:0,
                 from hellow.cpp:1:
/usr/include/c++/7/ostream:391:7: note: declared protected here
       basic_ostream(const basic_ostream&) = delete;
       ^~~~~~~~~~~~~
hellow.cpp:14:29: error: use of deleted function ‘std::basic_ostream<_CharT, _Traits>::basic_ostream(const std::basic_ostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]’
  std::ostream stream = std::cout;
                             ^~~~
In file included from /usr/include/c++/7/iostream:39:0,
                 from hellow.cpp:1:
/usr/include/c++/7/ostream:391:7: note: declared here
       basic_ostream(const basic_ostream&) = delete;
       ^~~~~~~~~~~~~
hellow.cpp:16:17: error: ‘std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator=(const std::basic_ostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]’ is protected within this context
   stream = std::cerr;
                 ^~~~
In file included from /usr/include/c++/7/iostream:39:0,
                 from hellow.cpp:1:
/usr/include/c++/7/ostream:399:22: note: declared protected here
       basic_ostream& operator=(const basic_ostream&) = delete;
                      ^~~~~~~~
hellow.cpp:16:17: error: use of deleted function ‘std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator=(const std::basic_ostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]’
   stream = std::cerr;
                 ^~~~
In file included from /usr/include/c++/7/iostream:39:0,
                 from hellow.cpp:1:
/usr/include/c++/7/ostream:399:22: note: declared here
       basic_ostream& operator=(const basic_ostream&) = delete;
                      ^~~~~~~~
hellow.cpp:14:15: warning: reference to local variable ‘stream’ returned [-Wreturn-local-addr]
  std::ostream stream = std::cout;
               ^~~~~~
hoge@hoge-VirtualBox:~/cTest$

ry · 2019-05-16 06:54:49

c++ は不勉強なので的を外しているかもしれませんが、以下 URL が回答になるのではないでしょうか。
std::cout のみならず std::cerr を代入する箇所もエラーになっているみたいですし。

13.2 ストリームオブジェクトのコピーと割り当て

hellow201905 · 2019-05-16 10:26:39

ありがとうございます。

教えていただいたページを参考に修正したところうまくいきました。
coutのアドレスを参照すればよかったのですね。

コンパイル・実行できたソースです。

コード:

hoge@hoge-VirtualBox:~/cTest$ cat hellow.cpp 
#include <iostream>
#include <stdio.h>

#define STR(var) #var
enum LogLevel
{
    ERROR,
    INFO,
    DEBUG
};

std::ostream& logStream(LogLevel level);
std::ostream& logStream(LogLevel level) {
    std::ostream *stream = &std::cout;
    const char *szLevel = STR(INFO);
    if( level == ERROR ) {
        stream = &std::cerr;
        szLevel = STR(ERROR);
    } else if( level == DEBUG ) {
        szLevel = STR(DEBUG);
    }
    char szTime[90] = { 0 };
    time_t now = time(NULL);
    struct tm *pnow = localtime(&now);
    sprintf(szTime, "%04d/%02d/%02d %02d:%02d:%02d", pnow->tm_year + 1900, pnow->tm_mon + 1, pnow->tm_mday,
        pnow->tm_hour, pnow->tm_min, pnow->tm_sec);
    *stream << szTime << " [" << szLevel << "] ";

    return *stream;
}

int main() {
    logStream(INFO) << "Hellow." << std::endl;
    return 0;
}

Ubuntu日本語フォーラム

お知らせ

#1 2019-05-15 16:21:02

std::coutは変数に代入できないのでしょうか？

コード:

コード:

#2 2019-05-16 06:54:49

Re: std::coutは変数に代入できないのでしょうか？

#3 2019-05-16 10:26:39

Re: std::coutは変数に代入できないのでしょうか？

コード:

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