C++ clog 对象

❮ iostream 对象

int myNum = 12;

clog << "The number " << myNum << " was given\n";

定义和用法

The clog object is used to log messages about the state of the program. It behaves identically to cout but it can be directed to a different destination such as a log file. clog and cerr always write to the same destination.

For more detailed usage, see the <iostream> cout object.

While clog and cerr write to the same destination, clog is buffered and cerr is not. A buffered output stores the output temporarily in a variable and does not write to the destination until certain conditions are met. Buffered outputs are more efficient because they do fewer write operations on files. If the messages are important, use cerr instead because otherwise they may be lost if the program crashes.

注意: clog 对象是在 <iostream> 头文件中定义的。

更多示例

#include <iostream>
#include <fstream>
using namespace std;

int main() {
  int myNum = 12;

  // Set "info.log" as the output file for the log messages
  ofstream log("info.log");
  clog.rdbuf(log.rdbuf());
  
  // Write to the log file
  clog << "The number " << myNum << " was given\n";

  // Close the file
  log.close();
  
  return 0;
}

❮ iostream 对象