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DAY ONE : VARIABLE AND STRINGS, DATA TYPES, OPERATION, STRING INTERPOLATION, ARRAY
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import UIKit | |
//MARKS:- VARIABLES AND CONSTANTS | |
/* variables are data stored that can have their value change whenever we want it and constant are value that can not be changed .. advaantage of using var in declaring a variable and let in declaring a constant is that it help xcode to remind us of the constant we have set and whenever we try to change it, it will not xcode will not compile our code and it help to save memory space that is optimization of memory. */ | |
// create a name variable | |
var name = " James Bond" | |
// name can be updated without xcode throwing error message | |
//there is no need to redeclare it anymore | |
name = "Ade Osun" | |
// print what is in the name variable | |
print("\(name)") // Ade Osun is printed instead of James Bond and it is | |
//as a result of the variable name been updated | |
// let's create variable with let and try to change it | |
let address = " 17, James Bond Street" | |
// address has been alter and xcode will not run this code | |
// address = "8, Ade Osun Street" | |
//MARKS:- TYPES OF DATA | |
// 1. String : they are combination of characters | |
//it could be of million characters as the case maybe | |
// string declaration | |
var country = "Nigeria" //first method is type inference: is when //swift assing a datatype to variable or //constant base on the type of value assign //to the variable | |
var nation: String //second method is type annotation method | |
nation = "Nigeria" | |
//2. Integer: they are positive whole numbers | |
var age: Int | |
age = 25 | |
//MARKS:- type safety is observe in swift and it simply means swift will not allow one to put values in a variable declared as Int into string variable | |
//age = "James Bond" /* swift will throw up error since age has been declared as an integer initially */ | |
//3. FLOAT AND DOUBLE: these are use for decimal numbers and double is prefer to float because it holds more accuracy than float that is it can take more fractional digit than float | |
var latitude : Double | |
latitude = 36.1666677888 //36.1666677888 more accuracy | |
var longitude : Float | |
longitude = 36.1666677888 // 36.16667 less accuracy | |
//4. BOOLEAN: this is a data type that helps to set value to true, false or absolute | |
// Declaring variable as a boolean | |
var stayOutTooLate: Bool | |
stayOutTooLate = true | |
// it can also be declare this way | |
var comeHomeTooLate: Bool = true | |
//MARKS:- OPERATORS: These are the little symbols we learnt in our arithmetics | |
var a = 10 | |
a = a + 1 /* top up the value of a with 10 and it will make it 11 | |
a = a - 1 reduce the current value of a by 1 and it will make it 10 | |
a = a * a multiply the current value of a by itself and it will make it 100 */ | |
var b = 10 | |
b += 10 // b is now 20 | |
b -= 10 // b is now 10 | |
var c = 1.1 | |
var d = 2.2 | |
var e = c + d // this will add the decimals together and gives 3.3 | |
var name1 = "Tim McGraw" | |
var name2 = "Romeo" | |
var both = name1 + " and " + name2 // Tim McGraw and Romeo | |
var m = 9 | |
var f = 2 | |
var result = m % f // this returns the remainder and it is 1 | |
// comparison operators are: < , > , <= , >= , == , != | |
// they help to compare lefthand side operand to the righthand side | |
c > d // is c greater than d if yes then true | |
c >= e // is c greater than or equal to if yes then true | |
// you can negate a boolean with ! and it changes it to false if it is true | |
//MARKS:- STRING INTERPOLATION | |
// This is a way of combining variable and constant inside a string | |
var namee = "Tim McGraw" | |
var age1 = 25 | |
var latitude1 = 36.166667 | |
"Your name is \(namee), your age is \(age), and your latitude is \(latitude)." | |
// mathematical operation can be perform in string interpolation as well | |
"Your age is \(age1) and in 4 years, you will be \(age + 4)" | |
// output will be Your age is 25 and in 4 years, you will be 29years | |
//MARKS:- ARRAY | |
// swift use type inference to know what type of data your array holds | |
//it allows you group of data together into collections | |
//and allow you access those values in the array using the index. | |
var evenNumbers = [ 2, 4, 6, 8] | |
var songs = [ "Shake it off", "You belong with me", "Back to December" ] | |
// accessing the position of items in the array, you need to use the array name | |
//then the position . the first element is at index 0 and so on | |
songs[0] // Shake it off | |
songs[1] // You belong with me | |
// if you need to confirm the type of data the array holds | |
type(of: songs) // this is seeing songs as an array of strings | |
// if you want an array to take any type then you have to declare it as array of Any | |
var street:[Any] = [ "4, Ohemene Street", "14, kemi Adeosun", "17, Ayoola Street"] | |
// empty array declaration | |
var song: [String] = [] // empty array | |
song[0] = "Shake it Off" // assign the string Shake it Off to index 0f | |
// the array | |
var songs1 = [ "Shake it off", "You belong with me", "Back to December" ] | |
var songs2 = [ "let's go home", "Where have you been", "It's public holiday" ] | |
var both1 = songs1 + songs2 | |
// or | |
songs1 += songs2 | |
// You can append strings to an array |
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Check out this sample gist I created for your reference:
https://gist.github.com/wptechprodigy/94aee9c38af27dc87f79cbb2607aeb5f