c - fgets 在 while 循环中挂起

Question

已解决:在打开 qfile 之前关闭 infile 时已修复。

我正在尝试用 c 语言处理两个文件。对于第一个文件，我按行读取然后处理字符串。我正在使用 fgets，但是当 while 循环处于最后一次迭代时它只是挂起。我有:

//Not complete code. While loop is all that is in method that uses the file. 
//File I/O error checking is in place, does not assume there is always a file in argv[2]
FILE *infile;
FILE *qfile;

struct tree{
    char *name;
    char *id;
    char *permission;
    struct tree *next;
 };
 struct tree *root;
 struct tree *current;

int main(int argc, char *argv[]){
 //proper file i/o error checking in place 
  infile = fopen(argv[1], "r");
  if(infile != NULL)
     fill();//process first file
   qfile = fopen(argv[2], "r");
   if(qfile != NULL)
      find();//process second file
   }

void fill(void){
   char buffer[256];
   int first = 1;
   while(fgets(buffer,sizeof(buffer),infile) != NULL)
   {
      if(first && buffer[0] == "X")
      {
         root = (struct tree *)malloc(sizeof(struct tree));
         current = root;
         process(buffer, current);
         first = 0;
      }
      else if(buffer[0] == 'F')//siblings
      {
         current->next = (struct tree *)malloc(sizeof(struct tree));
         current = current->next;
         process(buffer, current);
      }
}

void process(char buffer[], struct tree *current)
{
    char *left;
    char *right;
    left = buffer;
    right = buffer;
    while(*left == 'F')
    {
            left++;
    }
    while(*right != ':')
    {
            right++;/*
            if(*right == ' ')
                    continue;*/

    }

    //assign name to current node
    current->name = (char *)malloc(sizeof(char)*(right-left));
    strncpy(current->name, left, right-left);
    left = right + 1;
    while(*right != '=')
    {
            right++;
    }

    //assign property to current node
    current->property = (char *)malloc(sizeof(char)*(right-left));
    strncpy(current->property, left, right-left);

    left = right + 1;
    while(oright != '\n')
    t = (struct tree *)malloc(sizeof(struct tree));
                    current = root;
                    process(buffer, current);
                    //root->name = buffer;

                    first = 0;
            }
            else if(buffer[0] == 'F')//siblings
            {
                    current->next = (struct tree *)malloc(sizeof(struct tree));
                    current = current->next;
                    process(buffer, current);

    {       right++;}

    //assign value to current node
    current->value = (char *)malloc(sizeof(char)*(right-left));
    strncpy(current->value, left, right-left);
    printf("Name =%s\nProperty=%s\nValue=%s\n", current->name,current->property,current->value);
    }

它遍历整个文件，然后卡在 while 循环中。这只处理第一个文件。当我不包含第二个文件(进程标准输入)时，它不会挂起。当它确实挂起时，它会检查所有条件并在循环底部停止。文件的最后一行本身就是一个换行符。

什么可能导致循环挂起？使用 64 位 Linux。

编辑:适当的文件 I/O 检查到位。不完整的代码，因为我将问题缩小到 fill() 中的 while 循环。 fill() 只处理第一个文件。第二个文件由 find() 处理，这是一种不同的方法。问题仅出在第一个文件上。第一个文件仅在 fill() 中使用。

EDIT2:发布完整代码，打印语句用于跟踪。 抱歉给您带来了困惑。

Answer 1

首先始终检查 I/O

首先检查你的程序是否有足够数量的参数，因为你使用了 argv[1] 然后检查是否成功打开文件

例如

if ( --argc )
{
  infile = fopen(argv[1], "r");
  if ( infile != NULL )
  {
    // do your fgets stuff
    fclose(infile);
  }
}