fscanf()

(PHP 4 >= 4.0.1, PHP 5, PHP 7)

从文件中格式化输入

说明

fscanf()函数和sscanf()相似，但是它从与$handle关联的文件中接受输入并根据指定的$format（定义于sprintf()的文档中）来解释输入。

格式字符串中的任何空白会与输入流中的任何空白匹配。这意味着甚至格式字符串中的制表符t也会与输入流中的一个空格字符匹配。

每次调用fscanf()都会从文件中读取一行。

参数

文件系统指针，是典型地由fopen()创建的resource(资源)。

参数格式是sprintf()文档中所描述的格式。

The optional assigned values.

返回值

如果只给此函数传递了两个参数，解析后的值会被作为数组返回。否则，如果提供了可选参数，此函数将返回被赋值的数目。可选参数必须用引用传递。

更新日志

范例

Example #1fscanf()例子

users.txt 的内容

javier  argonaut        pe
hiroshi sculptor        jp
robert  slacker us
luigi   florist it

参见

• fread() 读取文件（可安全用于二进制文件）
• fgets() 从文件指针中读取一行
• fgetss() 从文件指针中读取一行并过滤掉 HTML 标记
• sscanf() 根据指定格式解析输入的字符
• printf() 输出格式化字符串
• sprintf()Return a formatted string

For C/C++ programmers.
fscanf() does not work like C/C++, because PHP's fscanf() move file pointer the next line implicitly.

It would be great to precise in the fscanf documentation
that one call to the function, reads a complete line.
and not just the number of values defined in the format.
If a text file contains 2 lines each containing 4 integer values,
reading the file with 8 fscanf($fd,"%d",$v) doesnt run !
You have to make 2 
fscanf($fd,"%d %d %d %d",$v1,$v2,$v3,$v4);
Then 1 fscanf per line.

If you want to read text files in csv format or the like(no matter what character the fields are separated with), you should use fgetcsv() instead. When a text for a field is blank, fscanf() may skip it and fill it with the next text, whereas fgetcsv() correctly regards it as a blank field.

If you want to parse a cron file, you may use this pattern: 

Yet another function to read a file and return a record/string by a delimiter. It is very much like fgets() with the delimiter being an additional parameter. Works great across multiple lines.
function fgetd(&$rFile, $sDelim, $iBuffer=1024) {
  $sRecord = '';
  while(!feof($rFile)) {
    $iPos = strpos($sRecord, $sDelim);
    if ($iPos === false) {
      $sRecord .= fread($rFile, $iBuffer);
    } else {
      fseek($rFile, 0-strlen($sRecord)+$iPos+strlen($sDelim), SEEK_CUR);
      return substr($sRecord, 0, $iPos);
    }
  }
  return false;
}

actually, instead of trying to think of every character that might be in your file, excluding the delimiter would be much easier.
for example, if your delimiter was a comma use:
%[^,]
instead of:
%[a-zA-Z0-9.| ... ]
Just make sure to use %[^,\n] on your last entry so you don't include the newline.

to include all type of visible chars you should try: 

fscanf works a little retardedly I've found. Instead of using just a plain %s you probably will need to use sets instead. Because it works so screwy compared to C/C++, fscanf does not have the ability to scan ahead in a string and pattern match correctly, so a seemingly perfect function call like:
fscanf($fh, "%s::%s");
With a file like:
user::password
Will not work. When fscanf looks for a string, it will look and stop at nothing except for a whitespace so :: and everything except whitespace is considered part of that string, however you can make it a little smarter by:
fscanf($fh, "%[a-zA-Z0-9,. ]::%[a-zA-Z0-9,. ]" $var1, $var2);
Which tells it that it can only accept a through z A through Z 0 through 9 a comma a period and a whitespace as input to the string, everything else cause it to stop taking in as input and continue parsing the line. This is very useful if you want to get a sentence into the string and you're not sure of exactly how many words to add, etc.

If you want fscanf()to scan one variable in a large number of lines, e.g an Ipadress in a line with more variables, then use fscanf with explode()

Besides, fscanf()is much faster than fgets()

The use of PHP code in the ACM submission
Here is a sample solution for problem 1001 using PHP:

鹏仔微信 15129739599 鹏仔QQ344225443 鹏仔前端 pjxi.com 共享博客 sharedbk.com