每秒写入一个当前时间，并且在每一行加上行号。我有时候会出现行号重叠的请况，是哪里有问题啊

Question

#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <string.h>
int main()
{
    FILE *fp;
    fp = fopen("time_log.txt", "a+");

    time_t ctime;
    struct tm *mlocaltime;
    long long int n = 1;
    char buff[24];
    fseek(fp, 0, SEEK_SET);
    while (fread(buff, sizeof(char), 24, fp) != 0)
    {
        n++;
    }
    while (1)
    {
        ctime = time(NULL);
        mlocaltime = localtime(&ctime);
        printf("%d-%d-%d %d:%d:%d\n", mlocaltime->tm_year + 1900, mlocaltime->tm_mon + 1, mlocaltime->tm_mday, mlocaltime->tm_hour, mlocaltime->tm_min, mlocaltime->tm_sec);
        fprintf(fp, "%d\t", n);
        fprintf(fp, "%d-%d-%d %d:%d:%d\n", mlocaltime->tm_year + 1900, mlocaltime->tm_mon + 1, mlocaltime->tm_mday, mlocaltime->tm_hour, mlocaltime->tm_min, mlocaltime->tm_sec);
        sleep(1);
        // fflush(fp);
        n++;
    }
}

Answer 1

是不是你有不止一个程序实例在运行