How to manage logs of C++ code?

With the continuous development of software development, log management has become an indispensable part of the code development process, and C, as a relatively complex programming language, is very important in code development. Log management is also required during development. This article will introduce the log management principles and specific implementation of C code, hoping to be helpful to readers.

1. Log management principles

1. Determine the log level

The log level represents the importance and urgency of the log information. In C development, log levels are divided into five levels: DEBUG, INFO, WARN, ERROR and FATAL, which respectively represent debugging information, general information, warning information, error information and serious exception information. Developers need to make choices based on actual conditions to minimize the impact on code performance.

2. Unified log format

The unified log format can facilitate log search, analysis and processing. In C, a commonly used log format is: yyyy-MM-dd hh:mm:ss.FFF[thread ID] message content, where the content in square brackets is the information that must be included, and can be adjusted according to needs.

3. Reduce coupling

Log management must affect the normal logic of the code as little as possible, and the corresponding log management code must be as independent as possible from the application code to ensure Keep your code clean and maintainable.

2. Code implementation

In C, the open source log library can be used for log management. The following introduces how to use log4cpp, a commonly used open source log library.

1. Install log4cpp

Under Ubuntu system, you can install it through the following command:

sudo apt-get install log4cpp

If using other operating systems, compile and install log4cpp through the corresponding package manager or manual download.

2. Create log configuration file

In C code, log management can be completed by reading a configuration file. First create a log configuration file named log4cpp.properties, for example:

log4j.rootLogger=DEBUG,rootAppender

log4j.appender.rootAppender=org.apache.log4j.ConsoleAppender

log4j.appender.rootAppender.layout=org.apache.log4j.PatternLayout

log4j.appender.rootAppender.layout.ConversionPattern=[%d] %p %m%n

log4j.logger.mylogger=DEBUG,myloggerAppender

log4j.additivity.mylogger=true

log4j.appender.myloggerAppender=org.apache.log4j.FileAppender

log4j.appender .myloggerAppender.File=./mylog.log

log4j.appender.myloggerAppender.layout=org.apache.log4j.PatternLayout

log4j.appender.myloggerAppender.layout.ConversionPattern=[%d ] %p %m%n

This configuration file specifies logging to the console and files, and logging to one of the custom loggers named mylogger, and also specifies the log output format.

3. Create C code

(1)Introduce the header file in the code by #include "log4cpp/Category.hh".

(2) Define a Category object, which represents a logger. For example:

log4cpp::Category& mylogger = log4cpp::Category::getInstance("mylogger");

(3) Pass mylogger.debug("debug message"); in the code to output logs, where debug can be replaced with other log levels.

4. Compile and run

After using the command line to compile the code, you can execute the generated executable file and check whether there is corresponding output on the console and log files.

3. Summary

Log management of C code can not only improve the quality of program development, but also provide necessary help for the efficient operation of the program. By introducing the principles of log management and the use of the log4cpp log library, this article hopes that readers can understand the log management method of C code and further master log management skills in practice.

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