How to determine whether a string is an integer in php

Two methods: 1. Use intval() to convert the string into an integer value, and then use the "==" operator to determine whether the integer value is equal to the original string. The syntax "intval($str)= =$str", if equal, it is an integer. 2. Use is_numeric() and strpos() to determine whether the string is a numeric string without a decimal point. The syntax is "!is_numeric($str)||strpos($str,".")!==false" and return false is an integer, and vice versa is not.

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

php determines the string Two methods to determine whether it is an integer

Method 1: Use the intval() function and the "==" operator to determine

• Use the intval() function to convert the string into an integer value

• Use the "==" operator to determine whether the integer value is equal to the original string

<?php
header("Content-type:text/html;charset=utf-8");
function f($str){
	$result = intval($str);
	if($result==$str){
    	echo "$str 字符串是整数<br><br>";
	}
	else{
	    echo "$str 字符串不是整数<br><br>" ;
	}
}

f("a678");
f("678");
f("3.14");
?>

Method 2: Use is_numeric() function and strpos() function to judge

• Use The is_numeric() function determines whether it is a number or a numeric string (integer and floating point number)

• Use strpos() to determine whether the number contains a decimal point--exclude floating point numbers

You only need to determine whether the string is a numeric string that does not contain a decimal point

<?php
header("Content-type:text/html;charset=utf-8");
function f($str){
	if(!is_numeric($str)||strpos($str,".")!==false){
	  echo "$str 字符串不是整数<br><br>";
	}else{
	  echo "$str 字符串是整数<br><br>";
	}
}

f("a678");
f("3.14");
f("67854");
?>

Instructions:

intval() function

intval() function is used to get the integer value of a variable.

intval() function returns the integer value of variable var by using the specified base conversion (default is decimal). intval() cannot be used with object, otherwise an E_NOTICE error will be generated and 1 will be returned.

int intval ( mixed $var [, int $base = 10 ] )

Parameter description:

• $var: The quantity value to be converted to integer.

• #$base: The base used for conversion.

If base is 0, the base used is determined by detecting the format of var:

• If the string includes "0x" ( or "0X"), use hexadecimal (hex); otherwise,

• If the string starts with "0", use octal (octal); otherwise,

• Decimal will be used.

Return value

• Returns the integer value of var on success, and returns 0 on failure. An empty array returns 0, a non-empty array returns 1.

• The maximum value depends on the operating system. The maximum signed integer range on 32-bit systems is -2147483648 to 2147483647. For example, on such a system, intval('1000000000000') would return 2147483647. On a 64-bit system, the maximum signed integer value is 9223372036854775807.

• String may return 0, although it depends on the leftmost character of the string.

is_numeric() function

is_numeric() function is used to detect whether a variable is a number or a numeric string.

bool is_numeric ( mixed $var )

Parameter description:

• $var: Variable to be detected.

Return value

• If the specified variable is a number or numeric string, it returns TRUE, otherwise it returns FALSE. Note that floating point type returns 1 , that is, TRUE.

strpos() function

strpos() function finds the first occurrence of a string in another string (size sensitive Write).

strpos($string,$find,$start)

Parameter description:

• $string: required. Specifies the string to be searched for.

• #$find: required. Specifies the characters to search for.

• $start: Optional. Specifies the location from which to start the search.

Return value:

• Returns the position of the first occurrence of a string in another string, or returns if the string is not found FALSE. Note: The string position starts from 0, not from 1.

Recommended study: "PHP Video Tutorial"

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