Constants, variables, and expressions

The idea

Swift uses let for a constant binding and var for a variable that can be reassigned. The compiler can infer a type from an initializer, but later assignments must remain compatible with that type. Integer and floating-point arithmetic are distinct. An integer division does not retain a fractional remainder, and Swift generally requires explicit numeric conversions when combining different numeric types.

String interpolation embeds expressions inside text using a backslash and parentheses. It is useful for labels without changing the underlying values. Swift strings represent Unicode text, so their positions are not ordinary integer array indices. Use supported string operations, and do not assume that the number of encoded bytes equals the number of visible characters.

let tasks = 11
let days = 3
let average = Double(tasks) / Double(days)
print(tasks / days)
print("Tasks: (tasks)")
print(average > 3.5)

3
Tasks: 11
true

Integer division yields three. Explicit conversions enable the fractional average, and interpolation includes the unchanged task count in a label.