What is the php function to get the first digits of a string?

#What is the function in php to get the first few digits of a string?

Usage of substr function:

substr Returns the substring of string

Instructions: string substr (string $string, int $ start [, int $length ] )

Returns the substring of string string specified by the start and length parameters.

Parameters

string

Input string .

start

• If start is a non-negative number, the returned string will start from the start position of string and start counting from 0. For example, in the string "abcdef", the character at position 0 is "a", the character at position 2 is "c", and so on.

• If start is a negative number, the returned string will start from the start character forward from the end of string.

• If the length of string is less than or equal to start, FALSE will be returned.

<?php
$rest = substr(“abcdef”, -1); // 返回 “f”
$rest = substr(“abcdef”, -2); // 返回 “ef”
$rest = substr(“abcdef”, -3, 1); // 返回 “d”
?>

length

• If a positive length is provided, the returned string will start at start at most Contains length characters (depending on the length of string).

• If a negative length is provided, many characters at the end of the string will be missed (if start is a negative number, it will be counted from the end of the string). If start is not in this text, an empty string will be returned.

• If length is supplied with a value of 0, FALSE or NULL, an empty string will be returned.

• If length is not provided, the returned substring will start at the start position and continue until the end of the string.

<?php
$rest = substr(“abcdef”, 0, -1); // 返回 “abcde”
$rest = substr(“abcdef”, 2, -1); // 返回 “cde”
$rest = substr(“abcdef”, 4, -4); // 返回 “”
$rest = substr(“abcdef”, -3, -1); // 返回 “de”
?>

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