| Liberty BASIC Help Online |
Numbers and Strings
Liberty BASIC has several functions that convert numeric values and strings.
Description:
This function returns a numeric value for stringExpression if stringExpression represents a valid numeric value or if it begins with a valid numeric value. If not, then zero is returned.
Usage:
print 2 * val("3.14") Produces: 6.28
print val("hello") Produces: 0
print val("3 blind mice") Produces: 3
| STR$( numericExpression ) |
Description:
This function returns a string expressing the result of numericExpression.
Usage:
age = 23
age$ = str$(age)
price = 2.99
price$ = str$(price)
totalApples = 37
print "Total number of apples is " + str$(totalApples)
| USING(templateString, numericExpression) |
Description:
This function formats numericExpression as a string using templateString. The rules for the format are similar to those in Microsoft BASIC's PRINT USING statement, but since using( ) is a function, it can be used as part of a larger BASIC expression instead of immediate output only. The template string consists of the character "#" to indicate placement for numerals, and a single dot "." to indicate placement for the decimal point. The template string must be contained within double quotation marks. If there are more digits contained in a number than allowed for by the template string, the digits will be truncated to match the template.
A template string looks like this:
amount$ = using("######.##", 1234.56)
As part of a larger expression:
notice "Your total is $" + using("####.##", 1234.5)
A template string can be expressed as a string variable:
template$ = "######.##"
amount$ = using(template$, 1234.56)
Using() may be used in conjunction with 'print'. The following two examples produce the same result:
amount$ = using("######.##", 123456.78)
print amount$
print using("######.##", 123456.78)
The using() function for Liberty BASIC 3 has been modified so that it rounds its output like PRINT USING does in other BASICs.
Usage:
' print a column of ten justified numbers
for a = 1 to 10
print using("####.##", rnd(1)*1000)
next a
'sample output from the routine above:
72.06
244.28
133.74
99.64
813.50
529.65
601.19
697.91
5.82
619.22
Description:
Returns a numeric decimal from a hexadecimal number expressed in a string. Hexadecimal values are represented by digits 0 - F. the hexadecimal number can be preceded by the characters "&H". The hexadecimal string must be enclosed in quote marks.
Usage:
print hexdec( "FF" )
or:
print hexdec( "&HFF")
Description:
Returns a string representation of a decimal number converted to hexadecimal (base 16)
Usage:
print dechex$( 255 )
prints...
FF
| EVAL$(code$) and EVAL(code$) |
Description:
Liberty BASIC now has two functions for evaluating BASIC code inside a running program. The eval() function evaluates the code and returns a numeric value, and the eval$() function works the same way but returns a string value. Both will execute the very same code, but the string function converts the result to a string if it isn't already one, and the numeric version of the function converts it to numeric values.
Evaluating to a string
Here we show how to evaluate code to a string, and what happens if you try to evaluate it to be a number.
'Let's evaluate some code that produces a non-numeric result
a$(0) = "zero"
a$(1) = "one"
a$(2) = "two"
code$ = "a$(int("+str$(rnd(1))+"*3))"
print "We will evaluate the code: "; code$
result$ = eval$(code$)
print result$
'Now let's use the eval function, which effectively does a
'val() to the result of the calculation. Converting a non
'numeric string to a numeric value results in zero.
result = eval(code$)
print result
Evaluating to a number
Here's an example of the most common type of code evaluation users will want to do: Numeric computation. Let's just make a short example that asks you to type an expression to evaluate.
'ask for an expression
input "Type a numeric expression>"; code$
answer = eval(code$)
print answer
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Liberty BASIC - http://www.libertybasic.com/