c - 缺少最后一个 IP 地址

Question

我有一个文件，我正在尝试将 IP 地址存储到一个数组中。我的计划是将数据存储到逗号或将地址后的字符存储到虚拟变量中。由于某种原因，我的代码工作到第二行。任何帮助都会很棒。

黑名单.csv:

46.30.45.65, good.recycle2learn.com
22.51.66.23, hothouse.com
83.98.11.48, monkeyhouse.com

代码:

void Blacklist()
{
  FILE *blist;
  char quotations = 0;

  blist = fopen("blacklist.csv", "r");
  if (blist == NULL)
  {
    //Quit if something goes wrong
    exit(EXIT_FAILURE);
  }

  for (int i = 0; i <= 3; i++)
  {
    fscanf(blist, "%d.%d.%d.%d,", &blacklist[i][0], &blacklist[i][1],
        &blacklist[i][2], &blacklist[i][3]);
    while (quotations != '\n')
    {
      fscanf(blist, "%c,", &quotations);
    }
  }

  for (int i = 0; i <= 3; i++)
  {
    printf("%d.%d.%d.%d\n", blacklist[i][0], blacklist[i][1], blacklist[i][2],
        blacklist[i][3]);
  }
}

Answer 1

阅读每一行后，您并没有重置您的 quotations 变量(考虑到它的用途，它的命名不是很好)。一旦到达第一个换行符，您的 while 循环将永远不会再次进入。如果您在调试器中运行代码，就会看到这种情况。

要么在读取 ip 地址后重置变量:

for (int i = 0; i < 3; i++) // <-- use < instead of <=
{
    fscanf(blist, "%d.%d.%d.%d,", &blacklist[i][0], &blacklist[i][1], &blacklist[i][2], &blacklist[i][3]);
    quotations = 0; // <-- add this
    while (quotations != '\n')
    {
        fscanf(blist, "%c", &quotations); // <-- no comma after %c
    }
}

或者使用 do..while 循环代替:

for (int i = 0; i < 3; i++)
{
    fscanf(blist, "%d.%d.%d.%d,", &blacklist[i][0], &blacklist[i][1], &blacklist[i][2], &blacklist[i][3]);
    do
    {
        fscanf(blist, "%c", &quotations);
    }
    while (quotations != '\n');
}

更新:也就是说，您的代码没有处理 csv 文件在每个 IP 条目之间包含空行的可能性(如您的问题所示)或在最后一个之后缺少换行符入口。要解决这些问题，请尝试使用 fgets() 或 getline() 将文件逐行读入本地缓冲区，使用 sscanf() 根据需要解析缓冲区。

int blacklist[3][4];
int numblacklist;

void Blacklist()
{
  FILE *blist;
  char line[64];

  memset(blacklist, 0, sizeof(blacklist));
  numblacklist = 0;

  blist = fopen("blacklist.csv", "r");
  if (blist == NULL)
  {
    //Quit if something goes wrong
    exit(EXIT_FAILURE);
  }

  while (fgets(line, 64, blist))
  {
    if (sscanf(line, "%d.%d.%d.%d,", &blacklist[numblacklist][0], &blacklist[numblacklist][1], &blacklist[numblacklist][2], &blacklist[numblacklist][3]) == 4)
    {
      numblacklist++;
      if (numblacklist == 3)
        break;
    }
  }

  fclose(blist);

  for (int i = 0; i < numblacklist; i++)
  {
    printf("%d.%d.%d.%d\n", blacklist[i][0], blacklist[i][1], blacklist[i][2], blacklist[i][3]);
  }
}

或者:

int blacklist[3][4];
int numblacklist;

void Blacklist()
{
  FILE *blist;
  size_t linelen;
  char *line;

  memset(blacklist, 0, sizeof(blacklist));
  numblacklist = 0;

  blist = fopen("blacklist.csv", "r");
  if (blist == NULL)
  {
    //Quit if something goes wrong
    exit(EXIT_FAILURE);
  }

  line = NULL;
  linelen = 0;

  while (getline(&line, &linelen, blist) != -1)
  {
    if (sscanf(line, "%d.%d.%d.%d,", &blacklist[numblacklist][0], &blacklist[numblacklist][1], &blacklist[numblacklist][2], &blacklist[numblacklist][3]) == 4)
    {
      numblacklist++;
      if (numblacklist == 3)
        break;
    }
  }

  free(line);
  fclose(blist);

  for (int i = 0; i < numblacklist; i++)
  {
    printf("%d.%d.%d.%d\n", blacklist[i][0], blacklist[i][1], blacklist[i][2], blacklist[i][3]);
  }
}