expChips' Tour of Swift // 1


These days, I accepted some easy problems on leetcode, in order to get familiar to a new programming language——Swift. In this series, I will write down basic syntax and come useful skills. Mostly, it’s my personal online note.


  // hello_world.swift
  print("hello, world!")

The code above will print "hello, world!\n", and it’s a complete program. I can run it in command line by tapping swift hello_world.swift. It’s obviously that this language has some feature of script language.

We can add a parameter to change the last character of the string, and by doing this, the print will not wrap:

  // hello_world_unwrap.swift
  print("hello, world!", terminator: "")

And another parameter separator: is also important. You can use it like terminator:


Swift’s comments are C++ like. For example:

// luv 🍟
/* luv 📦*/

It’s no need to explain more.

values, variables, and constants

Swift uses different keywords.

  import Darwin // use acos()

  let Pi = acos(0.0) * 2, r: Double = 1
  var s = Pi * r * r

btw. You can interctive with swift like ruby, just tap swift and enter.

You can provide a type annotation when you declare a constant or variable, to be clear about the kind of values the constant or variable can store.

If you provide an initial value for a constant or variable at the point that it’s defined, Swift can almost always infer the type to be used for that constant or variable.


  print(Int.max)    // 9223372036854775807
  print(Int32.max)  // 2147483647
  print(UInt.max)   // 18446744073709551615

Digitals can be separated by _:

  print(2_333_444_555) // 2333444555