Code for reading text files under more efficient PHP

fread: Calculate the length in bytes, read data according to the specified length and number of times, and stop after encountering the end or completing the specified length of reading.
fgets: Read the entire line, and stop when encountering a carriage return or line feed or the end. Used in text mode.
Read string function The function of fgets function is to read a string from the specified file into a character array.
The function call form is:
fgets (character array name, n, file pointer);
where n is a positive integer.
means that the string read from the file does not exceed n-1 characters.
Add the end of string mark' after the last character read