How to convert php string to integer

In PHP, you can convert strings to integers. This process is often called type conversion or casting. The process of converting a string to an integer uses the function intval() or the (int) operator. This article will introduce how to convert a string into an integer. The knowledge points involved are as follows:

1. Integer type (Integer) in PHP
2. String (String) in PHP
3. Use the intval function to convert a string to an integer type
4. Use the (int) operator to convert a string to an integer type
5. Notes and common errors

1. Integer type (Integer) in PHP

In PHP, integer type is a data type that represents integer numbers. Integer types can be positive, negative, or 0, with no decimal point or thousands separator. The range of integer types is usually -2147483648 to 2147483647. However, the upper and lower limits of this range may vary based on different PHP versions, different server settings, and different operating systems.

2. String in PHP

In PHP, string is a data type that represents text. Strings can contain letters, numbers, punctuation, and spaces. In PHP, strings can be represented by single quotes (') or double quotes ("). If there are single quotes in the string, then the string must be enclosed in double quotes and vice versa. In addition, in PHP, you can Use the period (.) to concatenate multiple strings together. For example:

$a = 'Hello';
$b = 'World';
echo $a . ' ' . $b; //Output: Hello World

3. Use the intval function to convert a string into an integer type

The intval function in PHP can be used to convert a string into an integer type. intval The function has two forms, one accepts a string as a parameter, and the other accepts two parameters. If only one parameter is passed, the intval function converts the parameter to an integer type. For example:

$ str = '123';
$int = intval($str);
echo $int; //Output: 123

If the string contains non-numeric characters, the intval function will It is ignored. For example:

$str = 'abc123';
$int = intval($str);
echo $int; //Output: 123

Also, The intval function also accepts an optional second argument for specifying the base. By default, the intval function treats strings as decimal numbers. However, the second argument can be used to specify a different base. Here In this case, the intval function converts the string into an integer in the corresponding base. For example:

$str = '0x1b';
$int = intval($str, 16); //Specify 16 Base
echo $int; //Output: 27

4. Use the (int) operator to convert the string into an integer type

In PHP, you can also use (int ) This operator converts a string to an integer. For example:

$str = '123';
$int = (int) $str;
echo $int; //Output: 123

Like the intval function, the (int) operator will also ignore non-numeric characters. For example:

$str = 'abc123';
$int = (int) $ str;
echo $int; //Output: 0

In addition, the (int) operator does not support the specified base, it can only treat strings as decimal numbers.

5. Precautions and common mistakes

• If the string starts with 0, the intval function and (int) operator treat it as an octal number. For example, the string '0123' is converted to the decimal number 83. If you want to treat the string as a decimal number, make sure to remove the leading zeros.
• Neither the intval function nor the (int) operator can convert floating point numbers to integers. If you want to convert a floating point number to an integer type, please use the floor, ceil or round function to round it before performing type conversion.
• Neither the intval function nor the (int) operator supports converting objects to integral types. If you want to convert an object to an integer type, use the object's __toString method or other methods to convert it to a string, and then use the preceding method to convert the string to an integer type.

Summary

In PHP, you can convert a string to an integer type using the intval function or the (int) operator. The intval function supports specifying the base; the (int) operator only supports treating strings as decimal numbers. During the conversion process, you need to pay attention to the fact that the string cannot contain non-numeric characters, leading zeros, etc., as well as the conversion method of floating point numbers and objects.

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