C程序卡住，甚至不进入主程序

Question

我为 FCFS 调度编写了以下代码。 问题是这段代码编译正常，但是执行./a.out后，什么也没有显示，程序卡住了。它甚至不打印 main() 开头的 "Reading" printf 语句。有什么问题？

#include <stdio.h>

struct process
{

  int at;
  int bt;
  int wt;
  int tt;
  int rt;
  char pid[5];

} p[5];

int i, j;
int n = 0;

void main()
{
  printf("Reading");
  FILE *fp;
  fp = fopen("in1.txt", "r");
  char sample;
  if (fp != NULL )
  {
    sample = getc(fp);
    while (sample != EOF);
    {
      if (sample == '\n')
        n++;
      sample = getc(fp);
    }
    fseek(fp, 0, 0);
    for (i = 0; i < n; i++)
    {
      fscanf(fp, "%s %d %d", p[i].pid, &p[i].at, &p[i].bt);
      p[i].wt = p[i].tt = 0;
      p[i].rt = p[i].bt;
    }
    fclose(fp);
  }
  //sorta();
  printf("\nGantt Chart for FCFS\n");

  int t = 0;
  int avgw = 0;
  int avgt = 0;
  printf("%d ", t);
  for (i = 0; i < n; i++)
  {
    if (p[i].at > t)
    {
      printf("%d ", t);
      t = p[i].at;
    }
    p[i].wt = t - p[i].at;
    avgw = avgw + p[i].wt;
    printf("%s ", p[i].pid);
    p[i].tt = p[i].bt + p[i].wt;
    avgt = avgt + p[i].tt;
    t = t + p[i].bt;
    printf("%d ", t);
    printf("\navg waiting time = %d", avgw / n);
    printf("\navg turn around time = %d", avgt / n);
  }
}

Answer 1

标准输出是行缓冲的。把“Reading”改成“Reading\n”，就可以看到了。

那你这里就错了:

while (sample!=EOF);

那个 while 循环的主体只是分号，而不是后面的 block !如果条件为真，您的程序将陷入无限循环。