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PHP stores whole numbers in a platform-dependent range. This range is typically that of 32-bit or 64-bit signed integers. [26] Integer variables can be assigned using decimal (positive and negative), octal, hexadecimal, and binary notations.
The mechanisms available for restricting data types include the ability to specify minimum and maximum values, regular expressions, constraints on the length of strings, and constraints on the number of digits in decimal values. XSD 1.1 again adds assertions, the ability to specify an arbitrary constraint by means of an XPath 2.0 expression.
A regular expression (shortened as regex or regexp), [1] sometimes referred to as rational expression, [2] [3] is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings , or for input validation .
In computer science, an integer literal is a kind of literal for an integer whose value is directly represented in source code.For example, in the assignment statement x = 1, the string 1 is an integer literal indicating the value 1, while in the statement x = 0x10 the string 0x10 is an integer literal indicating the value 16, which is represented by 10 in hexadecimal (indicated by the 0x prefix).
Data validation is intended to provide certain well-defined guarantees for fitness and consistency of data in an application or automated system. Data validation rules can be defined and designed using various methodologies, and be deployed in various contexts. [1]
For example, the hexadecimal representation of the 24 bits above is 4D616E. The octal representation is 23260556. Those 8 octal digits can be split into pairs (23 26 05 56), and each pair is converted to decimal to yield 19 22 05 46. Using those four decimal numbers as indices for the Base64 alphabet, the corresponding ASCII characters are TWFu.
A decimal data type could be implemented as either a floating-point number or as a fixed-point number. In the fixed-point case, the denominator would be set to a fixed power of ten. In the floating-point case, a variable exponent would represent the power of ten to which the mantissa of the number is multiplied.
The functions are simple data validation and data type checking functions. The data validation functions determine whether it is possible to convert or coerce the data value given as an argument to the function to the type implied by the function name, and return a Boolean value recording whether it was possible or not.