error: ‘logCallback’ was not declared in this scope

抱歉，我的代码中缺少了logCallback函数的声明，导致编译时出现了该错误。请将以下代码添加到main函数前面，即可解决该问题：

void logCallback(const rosgraph_msgs::Log::ConstPtr& log);

完整的C++代码示例如下：

#include <ros/ros.h>
#include <ros/console.h>
#include <rosgraph_msgs/Log.h>

void logCallback(const rosgraph_msgs::Log::ConstPtr& log);

int main(int argc, char **argv)
{
    ros::init(argc, argv, "log_listener");
    ros::NodeHandle nh;

    ros::Subscriber sub = nh.subscribe("/rosout", 1000, logCallback);

    ros::spin();

    return 0;
}

void logCallback(const rosgraph_msgs::Log::ConstPtr& log)
{
    // 解析日志信息
    std::string log_msg = log->msg;
    std::string log_level = log->level;
    std::string log_file = log->file;
    std::string log_line = std::to_string(log->line);
    std::string log_time = std::to_string(log->header.stamp.toSec());

    // 根据日志等级设置终端颜色
    if (log_level == "INFO") {
        ROS_INFO_STREAM("\033[32m" << "[" << log_level << "]" << "[" << log_file << "-" << log_line << "]" << "[" << log_time << "]" << ": " << log_msg << "\033[0m");
    } else if (log_level == "WARN") {
        ROS_WARN_STREAM("\033[33m" << "[" << log_level << "]" << "[" << log_file << "-" << log_line << "]" << "[" << log_time << "]" << ": " << log_msg << "\033[0m");
    } else if (log_level == "ERROR") {
        ROS_ERROR_STREAM("\033[31m" << "[" << log_level << "]" << "[" << log_file << "-" << log_line << "]" << "[" << log_time << "]" << ": " << log_msg << "\033[0m");
    } else if (log_level == "FATAL") {
        ROS_FATAL_STREAM("\033[35m" << "[" << log_level << "]" << "[" << log_file << "-" << log_line << "]" << "[" << log_time << "]" << ": " << log_msg << "\033[0m");
    }
}

请注意，我还将log->line和log->header.stamp.toSec()转换为了字符串类型，以便与其他字符串拼接。