实现了传输进去的字符串所在的文档，函数和行数显示功能。

实现了将传入的可变参数打印到日志功能。

#include<stdio.h>
#include<stdarg.h>
#include<string.h>

const char * g_path = "/home/exbot/wangqinghe/log.txt";
#define LOG(fmt,...) my_fprintf(__FILE__,__FUNCTION__,__LINE__,fmt,##__VA_ARGS__)

int my_fprintf(const char *pFileName,const char *pFunName,const long lLine,const char* fmt,...)
{
    printf("%s-%s-%d\n",__FILE__,__FUNCTION__,__LINE__);
    int iRet = -1;
    int i = 0;
    va_list args;
    va_start(args,fmt);
    FILE* fp = NULL;
    fp = fopen(g_path,"at+");

    int nFileNameLen = strlen(pFileName);
    char szLine[10] = {0};
    sprintf(szLine,"%ld",lLine);
    int nLineLen = strlen(szLine);
    int nSpaceLen = 30 - nFileNameLen - nLineLen;
    for(i = 0;  i < nSpaceLen; ++i)
    {
        fwrite(" ",1,1,fp);
    }
    fprintf(fp,"%s:%ld ",pFileName,lLine);
    iRet = vfprintf(fp,fmt,args);
    printf("iRet = %d\n",iRet);
    va_end(args);
    fflush(fp);    
    fclose(fp);
    return iRet;
}


int main()
{
    char *p = "this is my first debug";
    printf("%s-%s-%d\n",__FILE__,__func__,__LINE__);
    LOG("%s %d\n",p,1);
    return 0;
}    

输出结果：

exbot@ubuntu:~/wangqinghe/C/20190703$ gcc log.c -o log

exbot@ubuntu:~/wangqinghe/C/20190703$ ./log

log.c-main-41

log.c-my_fprintf-10

iRet = 25

在/home/exbot/wangqinghe/log.txt中有如下输出结果：

简单化版：

#include<stdio.h>
#include<stdarg.h>
#include<string.h>

const char * g_path = "/home/exbot/wangqinghe/log.txt";
#define LOG(fmt,...) my_fprintf(__FILE__,__FUNCTION__,__LINE__,fmt,##__VA_ARGS__)

int my_fprintf(const char *pFileName,const char *pFunName,const long lLine,const char* fmt,...)
{
    printf("%s-%s-%d\n",__FILE__,__FUNCTION__,__LINE__);
    int iRet = -1;
    int i = 0;
    va_list args;
    va_start(args,fmt);
    FILE* fp = NULL;
    fp = fopen(g_path,"at+");
    fprintf(fp,"%s:%ld ",pFileName,lLine);
    iRet = vfprintf(fp,fmt,args); //使用参数列表发送格式化输出到流stream中
    printf("iRet = %d\n",iRet);
    va_end(args);
    fflush(fp);    
    fclose(fp);
    return iRet;
}


int main()
{
    char *p = "this is my first debug";
    printf("%s-%s-%d\n",__FILE__,__func__,__LINE__);
    LOG("%s %d\n",p,1);
    //getchar();
    return 0;
}    

输出结果：