How to convert a string to integer in php

In PHP, converting strings to integers is a common operation. Because PHP is a weakly typed programming language, type conversion is often performed during the assignment and operation of variables and expressions.

When we need to convert a string into an integer, PHP provides several methods. The use of these methods is introduced below.

1. Use (int) cast character

(PHP 4, PHP 5, PHP 7)

This is a relatively common method , you only need to add the (int) cast character before the string to convert the string into an integer.

Sample code:

$str = "123";
$int = (int)$str;
echo $int; // 输出 123

It should be noted that "(int)" can only convert numbers in the string into integers. If the string contains non-numeric characters, it will only Returns 0, as in the following example:

$str = "123abc";
$int = (int)$str;
echo $int; // 输出 123

$str = "abc";
$int = (int)$str;
echo $int; // 输出 0

2. Use the intval() function

(PHP 4, PHP 5, PHP 7)

intval() function A string can be converted to an integer. If the string is not a complete integer, intval() only returns the first number. If the beginning of the string is not a number, 0 is returned.

Sample code:

$str = "123";
$int = intval($str);
echo $int; // 输出 123

$str = "123abc";
$int = intval($str);
echo $int; // 输出 123

$str = "abc";
$int = intval($str);
echo $int; // 输出 0

3. Use (double) cast character

(PHP 4, PHP 5, PHP 7)

(double) The cast character can convert a string into a floating point type. If the string contains non-numeric characters, 0 is returned.

Sample code:

$str = "123";
$int = (double)$str;
echo $int; // 输出 123

$str = "123.45";
$int = (double)$str;
echo $int; // 输出 123.45

$str = "abc";
$int = (double)$str;
echo $int; // 输出 0

4. Use sscanf() function

(PHP 4, PHP 5, PHP 7)

sscanf The () function can parse the formatted string, extract the numbers and convert them into integers. If the string contains no numbers, 0 is returned.

Sample code:

$str = "123";
sscanf($str, "%d", $int);
echo $int; // 输出 123

$str = "123abc";
sscanf($str, "%d", $int);
echo $int; // 输出 123

$str = "abc";
sscanf($str, "%d", $int);
echo $int; // 输出 0

To sum up, the above methods can convert strings into integers. Which method to use depends on personal habits and needs. However, it should be noted that if the string contains non-numeric characters, you need to choose a method based on the specific situation to prevent errors.

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