An integer is a number of the set ℤ = {..., -2, -1, 0, 1, 2, ...}.Syntax ¶Integers can be specified in decimal (base 10), hexadecimal (base 16), octal (base 8) or binary (base 2) notation, optionally preceded by a sign (- or +).Binary integer literals are available since PHP 5.4.0.To use octal notation, precede the number with a 0 (zero). To use hexadecimal notation precede the number with 0x. T..