php – fgets() and fread() – What is the difference?

fgets reads a line — i.e. it will stop at a newline.

fread reads raw data — it will stop after a specified (or default) number of bytes, independently of any newline that might or might not be present.

Speed is not a reason to use one over the other, as those two functions just don’t do the same thing :

• If you want to read a line, from a text file, then use fgets
• If you want to read some data (not necessarily a line) from a file, then use fread.

fread() for binary data and fread has a limit on how many chars you can read

$source_file = fopen( $filename, "r" ) or die("Couldn't open $filename");
while (!feof($source_file)) {
    $buffer = fread($source_file, 5);  
   var_dump($buffer); //return string with length 5 chars!
}

Number 5 is length bytes have been read .

The function fgets reads a single line from a text file. It is reading so long until the end of the current line (or the end of the file) is reached. Therefore, if you would like to read one line from a text file, you should use fgets.
The function fread not only reads until the end of the line but to the end of the file [e.g. fread($handle)] or as many bytes as specified as a parameter [e.g. fread($handle, 1024)]. So, if you would like to read a complete file, no matter whether it is a text file with all containing lines or arbitrary raw data from a file, you should use fread.

Both the functions are used to read data from files

fgets($filename, $bytes)
fgets usually reads $bytes-1 amount of data and stops at a newline or an EOF(end-of-file) whichever comes first. If the bytes are not specified, then the default value is 1024 bytes.

fread($filename, $bytes)
fread reads exactly $bytes amount of data and stops only at EOF.