如何一次性用log4cpp记录多个变量？

Question

如何使用log4cpp记录多个字符串？

E.g.如果我想记录所有的argv的主：

#include <iostream> 
#include <log4cpp/Category.hh> 
#include <log4cpp/FileAppender.hh> 
#include <log4cpp/PatternLayout.hh> 

using namespace std; 

int main(int argc, char* argv[]) { 
    log4cpp::Appender *appender = new log4cpp::FileAppender("FileAppender","mylog"); 
    log4cpp::PatternLayout *layout = new log4cpp::PatternLayout(); 
    layout->setConversionPattern("%d: %p - %m %n"); 
    log4cpp::Category& category = log4cpp::Category::getInstance("Category"); 
    appender->setLayout(layout); 
    category.setAppender(appender); 
    category.setPriority(log4cpp::Priority::INFO); 

    category.info("program started"); // this works fine, I see it in the logfile 

    for(int i=0; i<argc; ++i) { 
     // next line does not compile: 
     category.info("argv["<<i<<"] = '"<<argv[i]<<"'"); 
    } 

    return 0; 
} 

行

category.info("argv["<<i<<"] = '"<<argv[i]<<"'"); 

不能编译。很明显，记录器不能用作ostream。什么是log4cpp方式记录这样的事情，最好立刻？

Answer 1

你有两个选择：

• 使用printf-style formatting：

  for (int i = 0; i < argc; ++i) 
  { 
      category.info("argv[%d] = '%s'", i, argv[i]); 
  } 
  

• 使用infoStream()：

  for (int i = 0; i < argc; ++i) 
  { 
      category.infoStream() << "argv[" << i << "] = '" << argv[i] << "'"; 
  } 
  

我会去后者。