Swift Learning Note 3-4

Again a big dream, also can not resist you like to insist!

I ran and ran, just to catch up with the expectations of their own.

Third, operator + expression

Swift allows overloading of operators, such as "+" you can overload it

Follow-up details will be introduced

assignment operator Pass

arithmetic operators Most pass, only say special

19/4 result is 4 instead of 5//truncated rounding

Complete complex math operations with mathematical functions in <math.h> in the ANSI C standard library

Import Foundation

var b = Pow (3.2,5)//3.2 5-Time Square

var C = sqrt (3.2)//square root

0~10 random number var d = arc4random ()%10

var e = sin (1.57)//1.57 as radians

-Negative

overflow operator , which truncates the overflow data bit and makes the program more robust

&+, &-,&*,&/,&%

Signed integers, the highest bit is the sign bit, 0 is a positive number, and 1 represents a negative number.

The computer saves the integer in the form of complement, the complement of positive number is the same as the source code, the complement of negative number = Inverse code +1 (bitwise negation, the highest bit unchanged)

Displacement Operators :

The left shift n is equal to n times 2, and the right shift is divided by the N-squared of 2.

Range Operators :
A...B includes a A, B boundary. For in will use the

var range = 2...6

For NUM in range

{

Pringtln (num*5)

}

A.. <b when iterating through an array (you know, because it starts with 0)

Let books = ["OC", "Swift", "Java", "Go"]

For index in 0..<books.count

{

println (Books[index])

}

comparison operators : = = = Variables that determine the reference type, return ture when referencing the same object

logical operators :

Two will short-circuit: is the front expression judgment, the back is not judged, there is no chance of execution, direct results

&& False if False

& with but no short circuit

Three mesh operator :

var c =5, d = 5

C>d println ("C greater than D"):(C<d?println ("C less than D"):p rintln ("C equals D"))

Nil merge operator:??

A?? b Determine whether a is nil, not nil, return a value, nil, return the default B value, the requirement type must be consistent!

Example Let DefaultName = "Renhairui"

var name:string?= "Engineer"

println (name?? defaultname)//Output Engineer

var namenil:string?

println (namenil?? defaultname)//Output Renhairui

Actually a?? b equivalent to a!=nil? a!:b

Iv. Process Control

Branching structure

Loop structure

If else to deal with a small scope first

var age = 45

If Age >60

{

println ("seniors")
}

else if age>40{

println ("Middle-aged")

}else if age>20{
println ("Young people")

}

Switch does not continue to execute the next case

var score = "C"

Switch score

{
Case "A", "a":

println ("excellent")

Fallthrough through

Default

Break directly ignore

}

var score = 87

Switch score{

Case 91...100:

println ("excellent")

Case similarly

}

var somepoint = (x:1,y:-4)

Switch Sompoint

{

Case (0,0):

println ("origin")

Case (_,0):

println ("x-axis")

Case (0,_):

println ("Y-axis")

Case (0...int.max,0...int.max):

println ("First quadrant")

}

Case Value Binding

var score= 178

Switch score

{

Case 91...100:

println ("Youxiu")

Case 0..<60:

println ("")

Case Let Grade:

println ("Input score \ (grade) illegal")

}

var somepoint = (x:2,y:0)

Switch Somepoint

{

Case (0,0):

println ()

Case (Var x,0):

println ("on x axis, x value is \ (x)")

Case (0,var y):

println ("On y-axis, y value is \ (y)")

Case (x, y):

println ("Location: \ (x), \ (y)")

}

Where to add additional judging conditions to the case

Case var (x, y) where x>0 && y>0:

println ("\ (x), \ (y) in the first quadrant")

Loop Body: Code that is executed repeatedly

A For loop can specify multiple initializations at the same time, or it can be an expression that contains a logical operator

for var b= 0,s=0,p = 0; b<10 && s<4 &&p<10;p++

{

}

return can end the entire method function

break completely ends a loop, jumping out of the loop body, no matter in that loop.

continue ignores the remaining statements of this loop

Swift Learning Note 3-4