fscanf

(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)

fscanf — Parses input from a file according to a format

Description

fscanf(resource $stream, string $format, mixed &...$vars): array|int|false|null

The function fscanf() is similar to sscanf(), but it takes its input from a file associated with stream and interprets the input according to the specified format, which is described in the documentation for sprintf().

Any whitespace in the format string matches any whitespace in the input stream. This means that even a tab \t in the format string can match a single space character in the input stream.

Each call to fscanf() reads one line from the file.

Parameters

stream

A file system pointer resource that is typically created using fopen().

format

The format string is composed of zero or more directives: ordinary characters (excluding %) that are copied directly to the result and conversion specifications, each of which results in fetching its own parameter.

A conversion specification follows this prototype: %[argnum$][flags][width][.precision]specifier.

Argnum

An integer followed by a dollar sign $, to specify which number argument to treat in the conversion.

**Flags**
Flag	Description
`-`	Left-justify within the given field width; Right justification is the default
`+`	Prefix positive numbers with a plus sign `+`; Default only negative are prefixed with a negative sign.
(space)	Pads the result with spaces. This is the default.
`0`	Only left-pads numbers with zeros. With `s` specifiers this can also right-pad with zeros.
`'`(char)	Pads the result with the character (char).

Width

An integer that says how many characters (minimum) this conversion should result in.

Precision

A period . followed by an integer who's meaning depends on the specifier:

For e, E, f and F specifiers: this is the number of digits to be printed after the decimal point (by default, this is 6).
For g, G, h and H specifiers: this is the maximum number of significant digits to be printed.
For s specifier: it acts as a cutoff point, setting a maximum character limit to the string.

Note: If the period is specified without an explicit value for precision, 0 is assumed.

Note: Attempting to use a position specifier greater than PHP_INT_MAX will generate warnings.

**Specifiers**
Specifier	Description
`%`	A literal percent character. No argument is required.
`b`	The argument is treated as an integer and presented as a binary number.
`c`	The argument is treated as an integer and presented as the character with that ASCII.
`d`	The argument is treated as an integer and presented as a (signed) decimal number.
`e`	The argument is treated as scientific notation (e.g. 1.2e+2).
`E`	Like the `e` specifier but uses uppercase letter (e.g. 1.2E+2).
`f`	The argument is treated as a float and presented as a floating-point number (locale aware).
`F`	The argument is treated as a float and presented as a floating-point number (non-locale aware).
`g`	General format. Let P equal the precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. Then, if a conversion with style E would have an exponent of X: If P > X ≥ −4, the conversion is with style f and precision P − (X + 1). Otherwise, the conversion is with style e and precision P − 1.
`G`	Like the `g` specifier but uses `E` and `f`.
`h`	Like the `g` specifier but uses `F`. Available as of PHP 8.0.0.
`H`	Like the `g` specifier but uses `E` and `F`. Available as of PHP 8.0.0.
`o`	The argument is treated as an integer and presented as an octal number.
`s`	The argument is treated and presented as a string.
`u`	The argument is treated as an integer and presented as an unsigned decimal number.
`x`	The argument is treated as an integer and presented as a hexadecimal number (with lowercase letters).
`X`	The argument is treated as an integer and presented as a hexadecimal number (with uppercase letters).

Warning

The c type specifier ignores padding and width

Warning

Attempting to use a combination of the string and width specifiers with character sets that require more than one byte per character may result in unexpected results

Variables will be co-erced to a suitable type for the specifier:

**Type Handling**
Type	Specifiers
string	`s`
int	`d`, `u`, `c`, `o`, `x`, `X`, `b`
float	`e`, `E`, `f`, `F`, `g`, `G`, `h`, `H`

vars

The optional assigned values.

Return Values

If only two parameters were passed to this function, the values parsed will be returned as an array. Otherwise, if optional parameters are passed, the function will return the number of assigned values. The optional parameters must be passed by reference.

If there are more substrings expected in the format than there are available within string, null will be returned. On other errors, false will be returned.

Examples

Example #1 fscanf() Example


<?php
$handle = fopen("users.txt", "r");
while ($userinfo = fscanf($handle, "%s\t%s\t%s\n")) {
    list ($name, $profession, $countrycode) = $userinfo;
    //... do something with the values
}
fclose($handle);
?>

Example #2 Contents of users.txt

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

User Contributed Notes 10 notes

down

yasuo_ohgaki at hotmail dot com ¶

23 years ago


For C/C++ programmers.



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

down

Bertrand dot Lecun at prism dot uvsq dot Fr ¶

16 years ago


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.

down

nico at nicoswd dot com ¶

10 years ago


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

<?php

while ($cron = fscanf($fp, "%s %s %s %s %s %[^\n]s"))
{

}

?>

down

worldwideroach at hotmail dot com ¶

18 years ago


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;
}

down

eugene at pro-access dot com ¶

22 years ago


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.

down

loco.xxx at gmail dot com ¶

17 years ago


to include all type of visible chars you should try:



<?php fscanf($file_handler,"%[ -~]"); ?>

down

robert at NOSPAM dot NOSPAM ¶

21 years ago


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.

down

-8

arentzen at religion dot dk ¶

16 years ago


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()
<?
$filename = "somefile.txt";
$fp = fopen($filename, "r") or die ("Error opening file! \n");
$u = explode(" ",$line); // $u is the variable eg. an IPadress
while ($line = fscanf($fp,"%s",$u)) {
if(preg_match("/^$u/",$_SERVER['REMOTE_ADDR'])) {$badipadresss++;} // do something and continue scan
}
?>
Besides, fscanf()is much faster than fgets()

down

-6

james at zephyr-works dot com ¶

22 years ago


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.

down

-15

hdh265 at 163 dot com ¶

9 years ago


The use of PHP code in the ACM submission
Here is a sample solution for problem 1001 using PHP:
<?php
while (fscanf(STDIN, "%d%d", $a, $b) == 2) {
    print ($a + $b) . "\n";
}

add a note

fscanf

Description

Parameters

Argnum

Width

Precision

Return Values

Examples

See Also

User Contributed Notes 10 notes