Introduction to PHP data types: integer types and floating point numbers_PHP Tutorial

Syntax: Integer values ​​can be expressed in decimal, hexadecimal or octal, and can be preceded by an optional symbol (- or +). Octal represents a number that must be preceded by 0 (zero), and hexadecimal represents a number that must be preceded by 0x.

$int1=100; //Decimal
$int2=-123; //Negative number
$int3=0123; //Octal number
$int4=0x1A; //Hexadecimal number

echo PHP_INT_SIZE; //Display an integer represented by several bytes
echo "
";
echo PHP_INT_MAX;echo "
"; //The maximum number of integers (2147483647)
$fmax=2147483648;
var_dump(PHP_INT_MAX); //A number beyond the range of integer will be Interpreted as float type.
echo "
";
var_dump($fmax);

Floating point number: Floating point number (double or real number)
$a=1.34;
$b=1.8e308;
$c=8e-10;
var_dump($b);
//The word length of floating point numbers is platform-dependent, although usually the maximum value is 1.8e308 and has a precision of 14 decimal digits (cannot exceed 14 digits)
// The precision is calculated from the first non-zero number starting from the left.

For example: $a=567.9999899 //Output 567.9999899

$b=789.8812345678543 //Output 789.88123456785

$c=0.000000008907777777 //Output 0.000000008907777777

Important understanding: The accuracy should be calculated from the first non-0 number starting from the left.

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