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The pipe '|' is the composition operator. Due to the way pipelines work, it is only normally possible to pass one "argument" at a time in the form of a pair of standard input/output stream. Although extra file descriptors can be opened from named pipes, this no longer constitutes a point-free style.
Examples of a pipe-delimited standard data format are LEDES 1998B and HL7. It is frequently used because vertical bars are typically uncommon in the data itself. Similarly, the vertical bar may see use as a delimiter for regular expression operations (e.g. in sed).
In computer science, a Boolean expression is an expression used in programming languages that produces a Boolean value when evaluated. A Boolean value is either true or false.A Boolean expression may be composed of a combination of the Boolean constants True/False or Yes/No, Boolean-typed variables, Boolean-valued operators, and Boolean-valued functions.
In all versions of Python, boolean operators treat zero values or empty values such as "", 0, None, 0.0, [], and {} as false, while in general treating non-empty, non-zero values as true. The boolean values True and False were added to the language in Python 2.2.1 as constants (subclassed from 1 and 0 ) and were changed to be full blown ...
Python's is operator may be used to compare object identities (comparison by reference), and comparisons may be chained—for example, a <= b <= c. Python uses and, or, and not as Boolean operators. Python has a type of expression named a list comprehension, and a more general expression named a generator expression. [78] Anonymous functions ...
Examples: 0 or 0 = 0; 0 or 1 = 1; 1 or 0 = 1; 1 or 1 = 1; 1010 or 1100 = 1110; The or operator can be used to set bits in a bit field to 1, by or-ing the field with a constant field with the relevant bits set to 1. For example, x = x | 0b00000001 will force the final bit to 1, while leaving other bits unchanged. [citation needed]
The filters provide some treatments on an expression, when placed after it, separated by pipes. For example: [6] capitalize: changes a string's first letter to capital. upper: changes a whole string to capital. first: displays the first line of an array. length: returns a variable size.
As an example, although DOS allows the "pipe" syntax, it employs this second approach. Thus, suppose some long-running program "Worker" produces various messages as it works, and that a second program, TimeStamp copies each record from stdin to stdout , prefixed by the system's date and time when the record is received.