Swift Grammar Chapter

The problem of assigning a variable value

1) constant let (it can be declared without assigning a value, but only once), variable var.

2) When the declaration is assigned, the compiler automatically calculates the type.

3) The display defines the variable type.

Let value:float = 4.0f

4) If you need to convert a value to a different type, use a cast.

Let AAA = 90;let bbb = ' Hello, world '; let CCC = BBB + String (AAA);

5) use \ () to convert the value to String

var a:int = 10;var B:int = 5;println ("sum = \ (A + B);");

6) array, dictionary generation　　

Second, control flow

In a if statement, the condition must be a Boolean expression-which means that if score { ... } code like this will make an error without being cloaked in comparison with 0.

var array = ["A", "B", "C", "D", "E"];array[4] = "Apple";p rintln (array);        var dict = ["Key1": "Value1", "Key2": "value2"];d ict["Key3"] = "Value3";p rintln (dict);        Null dictionary and empty array var emptyarray = [string] (), var emptydict = [string, float] (), var emptydictarray = [[[String, Float]] ();

　　

　　

Swift Grammar Chapter