使用C语言设计编写程序日志，实现时间戳、 日志级别、日志内容、 日志输出、 日志轮转功能，，日志文件创建生成在temp文件目录下，其中日志轮转功能具体指的是指生成的所有日志文件超出temp目录规定容量后，删除最早生成的一个日志文件，只给出完整具体的log.c，log.h和测试代码main

log.h：

#ifndef _LOG_H
#define _LOG_H

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define DEFAULT_LOG_SIZE 1024 * 1024 * 10 // 默认日志文件大小为 10 MB
#define DEFAULT_LOG_NUM 10 // 默认日志文件数量为 10 个

#define LOG_LEVEL_DEBUG 0
#define LOG_LEVEL_INFO 1
#define LOG_LEVEL_WARN 2

#define LOG_DEBUG(fmt, args...) log_write(LOG_LEVEL_DEBUG, __FILE__, __FUNCTION__, __LINE__, fmt, ##args)
#define LOG_INFO(fmt, args...) log_write(LOG_LEVEL_INFO, __FILE__, __FUNCTION__, __LINE__, fmt, ##args)
#define LOG_WARN(fmt, args...) log_write(LOG_LEVEL_WARN, __FILE__, __FUNCTION__, __LINE__, fmt, ##args)

int log_init(const char* log_dir, const char* log_filename, int log_size, int log_num);
int log_write(int level, const char* file, const char* func, int line, const char* fmt, ...);
void log_destroy();

#endif

log.c：

#include "log.h"

static char g_log_dir[256] = "./"; // 日志目录
static char g_log_filename[256] = "log"; // 日志文件名
static int g_log_size = DEFAULT_LOG_SIZE; // 日志文件大小限制
static int g_log_num = DEFAULT_LOG_NUM; // 日志文件数量限制

static int g_log_fd = -1; // 当前日志文件描述符
static int g_log_size_cur = 0; // 当前日志文件大小
static int g_log_num_cur = 0; // 当前日志文件序号

static void log_rotate();

int log_init(const char* log_dir, const char* log_filename, int log_size, int log_num) {
    if (log_dir != NULL && strlen(log_dir) > 0) {
        strcpy(g_log_dir, log_dir);
    }
    if (log_filename != NULL && strlen(log_filename) > 0) {
        strcpy(g_log_filename, log_filename);
    }
    if (log_size > 0) {
        g_log_size = log_size;
    }
    if (log_num > 0) {
        g_log_num = log_num;
    }

    char log_path[512] = {0};
    sprintf(log_path, "%s%s.log.%d", g_log_dir, g_log_filename, g_log_num_cur);
    g_log_fd = open(log_path, O_CREAT | O_WRONLY | O_APPEND, 0644);
    if (g_log_fd == -1) {
        printf("log_init: open log file failed\n");
        return -1;
    }

    g_log_size_cur = lseek(g_log_fd, 0, SEEK_END);
    if (g_log_size_cur == -1) {
        printf("log_init: lseek log file failed\n");
        return -1;
    }

    return 0;
}

int log_write(int level, const char* file, const char* func, int line, const char* fmt, ...) {
    if (g_log_fd == -1) {
        printf("log_write: log is not initialized\n");
        return -1;
    }

    char log_buf[2048] = {0};
    time_t now = time(NULL);
    struct tm* tm_now = localtime(&now);
    sprintf(log_buf, "[%04d-%02d-%02d %02d:%02d:%02d] ",
            tm_now->tm_year + 1900, tm_now->tm_mon + 1, tm_now->tm_mday,
            tm_now->tm_hour, tm_now->tm_min, tm_now->tm_sec);
    switch (level) {
        case LOG_LEVEL_DEBUG:
            strcat(log_buf, "[DEBUG] ");
            break;
        case LOG_LEVEL_INFO:
            strcat(log_buf, "[INFO] ");
            break;
        case LOG_LEVEL_WARN:
            strcat(log_buf, "[WARN] ");
            break;
        default:
            strcat(log_buf, "[UNKNOWN] ");
            break;
    }
    sprintf(log_buf + strlen(log_buf), "[%s:%d:%s] ", file, line, func);

    va_list ap;
    va_start(ap, fmt);
    vsprintf(log_buf + strlen(log_buf), fmt, ap);
    va_end(ap);

    strcat(log_buf, "\n");

    int len = strlen(log_buf);
    if (g_log_size_cur + len > g_log_size) {
        log_rotate();
        char log_path[512] = {0};
        sprintf(log_path, "%s%s.log.%d", g_log_dir, g_log_filename, g_log_num_cur);
        g_log_fd = open(log_path, O_CREAT | O_WRONLY | O_APPEND, 0644);
        if (g_log_fd == -1) {
            printf("log_write: open log file failed\n");
            return -1;
        }
        g_log_size_cur = lseek(g_log_fd, 0, SEEK_END);
        if (g_log_size_cur == -1) {
            printf("log_write: lseek log file failed\n");
            return -1;
        }
    }

    int ret = write(g_log_fd, log_buf, len);
    if (ret == -1) {
        printf("log_write: write log failed\n");
        return -1;
    }
    g_log_size_cur += len;

    return 0;
}

void log_destroy() {
    if (g_log_fd != -1) {
        close(g_log_fd);
        g_log_fd = -1;
    }
}

static void log_rotate() {
    if (g_log_fd != -1) {
        close(g_log_fd);
        g_log_fd = -1;
    }

    char log_path[512] = {0};
    sprintf(log_path, "%s%s.log.%d", g_log_dir, g_log_filename, g_log_num_cur);
    unlink(log_path);

    g_log_num_cur = (g_log_num_cur + 1) % g_log_num;
}

main.c：

#include "log.h"

int main(int argc, char** argv) {
    log_init("./temp/", "test", 1024 * 1024 * 5, 3); // 初始化日志，日志文件大小为 5 MB，日志文件数量为 3 个
    LOG_DEBUG("test debug log");
    LOG_INFO("test info log");
    LOG_WARN("test warn log");
    log_destroy(); // 销毁日志

    return 0;
}

在 Linux 环境下编译运行即可。