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Julia Characters

A Char is a single character written inside single quotes. Every character also has a number code that Julia can reveal and use.

A Char is one character

Single quotes make a Char. Printing a Char shows the character alone, with no quotes.

letter = 'J'
println(letter)
println(letter == 'J')
println('x')

Character codes both ways

The Int function reveals the number code of a character. The Char function turns a code back into its character.

println(Int('A'))
println(Int('a'))
println(Char(97))
println(Char(66))

Moving and checking characters

Adding a whole number to a Char steps to a later character. The isletter and isdigit functions check what kind of character they are given.

println('a' + 1)
println('a' + 2)
println(isletter('a'))
println(isdigit('7'))
println(isdigit('a'))

Example

start = 'm'
println(start)
println(Int(start))
println(start + 1)
println(Char(Int(start) + 2))
println(isletter(start))
println(isdigit(start))

Key points

  • Single quotes: text in single quotes is one Char, never a String.
  • One only: a Char holds exactly one character, such as a letter, a digit, or a space.
  • Code number: Int(c) gives the number code of a character.
  • From a code: Char(n) gives the character that has the number code n.
  • Character arithmetic: adding a whole number to a Char moves that many steps through the character codes.
  • Checks: isletter(c) is true for a letter and isdigit(c) is true for a digit character.

In this example, start holds the character m. The lines print the character itself, its code 109, the next character n from adding 1, the character o built from the code plus 2, and two checks showing m is a letter but not a digit.

Note

a digit character such as '7' is text of length one, not the number 7.

Try it Yourself

Edit the code, then press Run.

Running is simulated · JuliaHub

Exercise

What does println(Char(65)) print?