BFOIT - Introduction to Computer Programming

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literal
A literal is a value in a program that is provided exactly as wanted, with no way for it to be changed.  It is sometimes referred to as a constant value.

The following examples show the use of literals in both Logo and Java.

 What Logo Java Procedure/Method Argument forward 100 forward( 100 ); Addition sum :inputParam 12.5 someVariable + 12.5 Equality equal? :inputParam 0 someVariable == 0

The first example shows the use of a literal ("100") as an argument in procedure/method invocations.

The second example shows the use of a literal ("12.5") in an arithmetic expression.

The third example shows the use of a literal ("0") in an equality expression.

Java's syntax specifies rules for how to express constants of a specific types in source code. Here is a summary:

boolean
the text: "true" or "false"
char
a single character or an escape sequence surrounded by apostrophe (single quote) characters

examples: 'A', '\t'

double
a real number between -1.7e308 and 1.7e308 with 14 significant figures of accuracy usually expressed in scientific notation and suffixed with a "d" or "D"

examples: 1.5D, 0.4e-2D

float
similar to double but in the range -3.4e38 through 3.4e38 and suffixed with an "f" or "F"
int
numbers in the range: -2147483648 through 2147483647 expressed in either octal, decimal, or hexadecimal formats. The first character(s) making up the number determine the radix:
• Octal int literals start with a zero and contain only the octal digits 0 - 7
• Decimal int literals are composed of one or more digits in the range of 0 - 9
• Hexadecimal literals start with the sequences "0x" or "0X" (that's zero followed by either an upper or lower case X) followed by characters 0 - 9 and/or a - f and/or A - F

examples: 0177, 127, and 0x7F (different representations of the same int value)

long
numbers in the range -92233720036854775808 through 92233720036854775807, expressed with the same rules as type int, but also terminated with an "l" or "L" character. You should always use the UPPER CASE variety since the lower case is easily confused with the number one.
String
A String literal is a group of characters surrounded by double quote characters

examples: "A string", "1234", "Two\nLines"

Other jargon:  A  B  C  D  E  F  G H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X Y Z

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This work (BFOIT: Introduction to Computer Programming, by Guy M. Haas),
identified by Berkeley Foundation for Opportunities in IT (BFOIT),
is free of known copyright restrictions.