Swift string characters

create string

	// 使用字符串字面量
	var stringA = "Hello, World!"
	print( stringA )

	// String 实例化
	var stringB = String("Hello, World!")
	print( stringB )

	Hello, World!
	Hello, World!

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string concatenation

• method one

	var stringA = "网址："
	stringA += "https://www.csdn.net/"
	print( stringA )

	网址：https://www.csdn.net/

• Method Two

	var varA   = 20
	let constA = 100
	var varC:Float = 20.0

	var stringA = "\(varA) 乘于 \(constA) 等于 \(varC * 100)"
	print( stringA )

	20 乘于 100 等于 2000.0

• method three

	let constA = "网址："
	let constB = "https://www.csdn.net/"
	var stringA = constA + constB
	print( stringA )

	网址：https://www.csdn.net/

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Other common properties of strings

• countAttribute: string length
• Use ==to compare two strings for equality
• hasPrefix(prefix: String): Check if a string has a specific prefix
• hasSuffix(suffix: String): Check if a string has a specific suffix
• Int(String): Convert a string number to an integer

---

create character

• cannot store more characters

	let char1: Character = "A"
	let char2: Character = "AB"
	// 正常输出
	print("char1 的值为 \(char1)")
	// 报错
	print("char2 的值为 \(char2)")

iterate over the characters in a string

	// swift3
	for ch in "Runoob".characters {
    
    
	    print(ch)
	}

	// swift4
	for ch in "Runoob" {
    
    
	    print(ch)
	}

string concatenation character

	var varA:String = "Hello "
	let varB:Character = "G"
	varA.append( varB )
	print("varC  =  \(varA)")