Literals

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=ProPgLiterals
• Last revised: 2022-05-21

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Non-variable compile-time string, numeric values and boolean values.

Literals are numbers, strings of characters or boolean truths specified directly in the source code. Literal values may be used by assigning them to a variable or constant, passing them to a procedure, or using them in an expression.

Numeric literals come in two forms - integer and floating-point.

Integer Literals

Decimal

Decimal digits ( 0 1 2 3 4 5 6 7 8 9 ).

Note: to get negative values, a "-" sign (Operator - (Negate)) can be placed before a numeric literal

start GeSHi

Dim x As Integer = 123456
Dim b As Byte = -128

end GeSHi

Hexadecimal

"&H", followed by hexadecimal digits ( 0 1 2 3 4 5 6 7 8 9 A B C D E F ).

start GeSHi

Dim x As Integer = &h1E240
Dim b As Byte = &H80

end GeSHi

Octal

"&O" (or "&"), followed by octal digits ( 0 1 2 3 4 5 6 7 )

start GeSHi

Dim x As Integer = &O361100
Dim b As Byte = &O200

end GeSHi

Binary

"&B", followed by binary digits ( 0 1 )

start GeSHi

Dim x As Integer = &B11110001001000000
Dim b As Byte = &B10000000

end GeSHi

Integer size suffixes

If an integer literal suffix is not given, the number field size required to hold the literal is automatically calculated. Specifying a size suffix guarantees that the compiler will consider a number as a specific integer size.

Integer literals ending with:

• "%", are considered as signed 32/64 (depending on platform) bit integers. (Integer)
• "L", "&", are considered as signed 32 bit long integers. (Long)
• "U", are considered as unsigned 32/64 (depending on platform) bit integers. (Uinteger)
• "UL", are considered as unsigned 32 bit integers. (Ulong)
• "LL", are considered as signed 64 bit integers. (Longint)
• "ULL", are considered as unsigned 64 bit integers. (Ulongint)

Negative (-) and positive (+) signs that prefix a numeric literal, are not part of the numeric literal. expressions (like "-1L") are parsed as the negate operator applied to the value represented by the positive literal ("1L"), which may involve implicit type conversions. Same behavior when an explicit "+" sign precedes the integer literal.

The prefixes, suffixes, and hexadecimal letter digits are all case-insensitive.

start GeSHi

Dim a As Long = 123L
Dim b As UInteger = &h1234u
Dim c As LongInt = 76543LL
Dim d As ULongInt = &b1010101ULL

end GeSHi

Floating Point Literals

Floating point numbers are specified in decimal digits, may be positive or negative, have a fractional portion, and optionally an exponent. The format of a floating point literal is as follows (without space or parenthesis added):

number[.[fraction]][(D|E)[+|-][exponent]][suffix]

or

.fraction[(D|E)[+|-][exponent]][suffix]

By default, floating point numbers that do not have either an exponent or a suffix are considered as a double precision floating point value, except in the -lang qb dialect, where numbers of 7 digits or fewer are considered to be single precision.

start GeSHi

Dim a As Double = 123.456
Dim b As Double = -123.0

end GeSHi

The letter "D" or "E", placed after the number/fraction part, allows the number to be given an exponent. The exponent may be specified as either positive or negative with a plus ("+") or minus ("-") sign. Exponents that do not have a sign are positive.

An exponent value is not required after the letter (or even after the sign), so the letter can be used on its own just to specify the type. "D" specifies a double-precision floating-point number. "E" specifies a floating-point number using the default precision. When the letter is used on its own in combination with a suffix (see below) the type denoted by the suffix overrules the type specified by the letter.

start GeSHi

Dim a As Double = -123.0d
Dim b As Double = -123e
Dim c As Double = 743.1e+13
Dim d As Double = 743.1D-13
Dim e As Double = 743.1E13
Dim f As Single = 743D!

end GeSHi

A suffix of "!" or "F" on a number specifies a single precision (32 bit total) floating point value. A suffix of "#" or "D" specifies a double precision float.

Note that the letter suffixes and exponent specifiers are all case-insensitive.

start GeSHi

Dim a As Single = 3.1!
Dim b As Single = -123.456e-7f
Dim c As Double = 0#
Dim d As Double = 3.141592653589e3#

end GeSHi

String Literals

String literals are a sequence of characters contained between two double quotes. The sequence of characters escaped or non-escaped.

Double quotes can be specified in the string literal by using two double quotes together.

start GeSHi

Print "Hello World!"
Print "That's right!"
Print "See the ""word"" contained in double quotes."

end GeSHi

String literals can contain escape sequences if the string literal is prefixed by the ! operator (Escaped String Literal). See Escape Sequences for a list of accepted escape sequences.

start GeSHi

Print !"Hello\nWorld!"

end GeSHi

By default, string literals are non-escaped unless Option Escape was used in the source in which case all string literals following are by default escaped.

A string may be explicitly specified as non-escaped when prefixed by the $ operator (Non-Escaped String Literal).

start GeSHi

Print $"C:\temp"

end GeSHi

Besides ASCII files with Unicode escape sequences (\u), FreeBASIC can parse UTF-8, UTF-16LE, UTF-16BE, UTF-32LE and UTF-32BE source files as long as they were saved with Byte Order Mark (BOM), allowing unicode characters directly in the string literal.

Note: The most reliable cross-platform code is obtained by encoding without BOM in ASCII/UTF-8 characters.

String literals in an ASCII file are treated as ZString, while string literals in a Unicode file are treated as WString (regardless of the string literal's value).

Boolean Literals

The boolean type has two values, represented by literals True and False.

start GeSHi

Dim a As Boolean = False
Dim b As Boolean = True

end GeSHi

See also

• Typeof
• #define
• Const
• Standard Data Types
• Table with variable types overview, limits and suffixes

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