Comparisons and logic · Lessons

Comparing values

Each comparison answers true or false. Most have a symbol and a word you can use instead, whichever reads better.

Write	Or	True when
`=`	`is`	the two are the same
`<>`	`is not`	they differ
`<` `>`		less than, greater than
`<=` `>=`		at most, at least

ExampleRun it in the playground

put 5 > 3
put 5 >= 5
put 5 <> 3
put 5 is not 3
put 5 = 5.0
put "cat" is "dog"

Output

true
true
true
true
true
false

Comparing text

Text is compared in alphabetical order, and xTalk does not mind capital letters unless you ask it to, with the property caseSensitive.

ExampleRun it in the playground

put "ABC" is "abc"
put "apple" < "banana"
set the caseSensitive to true
put "ABC" is "abc"

Output

true
true
false

Is it in there?

xTalk has comparisons for text inside text that read like English. These are some of its most used words.

ExampleRun it in the playground

put "Hello world" contains "world"
put "world" is in "Hello world"
put "Hello world" begins with "Hell"
put "report.pdf" ends with ".pdf"
put "z" is not in "abc"

Output

true
true
true
true
true

is among is stricter: it looks for a whole word, item or line, not just some characters.

ExampleRun it in the playground

put "b" is among the items of "a,b,c"
put "bc" is among the items of "a,b,c"
put "bc" is in "a,b,c"
put "fox" is among the words of "the quick brown fox"
put "Fri" is not among the items of "Sat,Sun"

Output

true
false
false
true
true

And, or, not

Combine conditions with and (both must be true), or (at least one) and not (the opposite). Brackets make your meaning plain.

ExampleRun it in the playground

put 7 into tAge
put tAge >= 5 and tAge <= 12
put tAge < 5 or tAge > 65
put not (tAge = 7)

Output

true
false
false

xTalk stops as soon as it knows the answer: if the left side of an and is false, the right side is never worked out. That lets you guard a test that would otherwise fail:

ExampleRun it in the playground

put 0 into tCount
if tCount > 0 and 100 / tCount > 10 then
   put "Big share"
else
   put "Nothing to share"
end if

Output

Nothing to share

Try it yourself

A year is a leap year when it divides by 4, unless it divides by 100, except that one that divides by 400 is a leap year after all. Write one expression that puts whether tYear is a leap year, and try it with 1900 and 2000.

Show a solution

ExampleRun it in the playground

put 1900 into tYear
put (tYear mod 4 is 0 and tYear mod 100 is not 0) or tYear mod 400 is 0
put 2000 into tYear
put (tYear mod 4 is 0 and tYear mod 100 is not 0) or tYear mod 400 is 0

Output

false
true

Words in this lesson

=is<>is not<><=>=containsis inbegins withends withis amongandornotcaseSensitive

Each one finds every lesson that uses it. The Dictionary has the whole story of each, with its syntax and more examples.