001_swift 字符串

//
//  main.swift
//  001_string
//
//  Created by liuan on 2020/3/22.
//  Copyright © 2020 liuan. All rights reserved.
//

import Foundation

//  字符串创建
var str1:String = "Hello";
var str2="Hello";
var str3=String(3);
var str4=String(5.2);
print(str1,str2,str3,str4)
//%ld 证书   %f %.2f 保留两位小数 %@ 对象
var str5=String(format: "第%ld", 1)
var str6=String(format: "价格：%.2f", 10.2)
print(str6)
//字符串操作
//1 获取长度
let count = str1.count;
print(count);
// 字符串判断是否为空
var str7 = "";
let ret1=str7.isEmpty;
let ret2=str1.isEmpty;
print(ret1,ret2);
//字符串遍历
for c in str1{
    print(c)
}
// 多个字符串组合成一个字符串
var str8 = str1+str2+str3+str4;
print(str8)
str1.insert(contentsOf:"AAA", at: str1.index(str1.startIndex,offsetBy: 2));
print(str1);
str1="Hello"
//字符串的判等 NSComparisonResult
let ret=str1.compare(str2);
print(ret)
//0 相等 -1不相等
print(ret.rawValue)
// 是否包含另一个字符串
let ret3=str1.contains(str2);
print(ret3);
//字符串的分割与合并
var str9="AaBaCaDaE";
let ret4 = str9.split(separator: "a");
print(ret4)
//合并
let ret5=ret4.joined()
print(ret5)
let ret6=ret4.joined(separator: "b");
print(ret6);

结果展示

Hello Hello 3 5.2
价格：10.20
5
true false
H
e
l
l
o
HelloHello35.2
HeAAAllo
NSComparisonResult
0
true
["A", "B", "C", "D", "E"]
ABCDE
AbBbCbDbE