Swift: Swift 运算符入门：算术比较逻辑运算符详解零基础教程

let currentRevenue = 250_000
let previousRevenue = 200_000
let growthRate = (currentRevenue - previousRevenue) / previousRevenue * 100
print("增长率：\(growthRate)%")

let currentRevenue = 250_000.0
let previousRevenue = 200_000.0
let growthRate = (currentRevenue - previousRevenue) / previousRevenue * 100
print("增长率：\(growthRate)%")

let a = 15
let b = 4
let sum = a + b      // 19
let diff = a - b     // 11
let prod = a * b     // 60
let quot = a / b     // 3（Int 除法截断小数）
let rem = a % b      // 3（15 / 4 = 3 余 3）

var score = 10
score += 5     // 等价于 score = score + 5 -> 15
score -= 3     // 等价于 score = score - 3 -> 12
score *= 2     // 等价于 score = score * 2 -> 24
score /= 4     // 等价于 score = score / 4 -> 6

// ============================================
// 统计月度支出汇总
// 演示算术和复合赋值运算符
// ============================================
var monthlyExpenses = 0.0
let rent = 1200.00
let groceries = 450.50
let transportation = 85.00
let entertainment = 200.00
monthlyExpenses += rent
monthlyExpenses += groceries
monthlyExpenses += transportation
monthlyExpenses += entertainment
let annualExpenses = monthlyExpenses * 12
let weeklyAverage = monthlyExpenses / 4.33
print("月度总支出：$\(monthlyExpenses)")
print("年度总支出：$\(annualExpenses)")
print("周均支出：$\(String(format: "%.2f", weeklyAverage))")

let age = 18
let isAdult = age >= 18     // true
let canDrive = age >= 16    // true
let isSenior = age > 65     // false
let userName = "Alice"
let isAdmin = userName == "Admin"  // false

let hasTicket = true
let isVip = false
let canEnter = hasTicket && isVip   // false
let canAccess = hasTicket || isVip  // true
let isNotVip = !isVip               // true

// ============================================
// 检查用户是否有权限访问管理后台
// 演示比较和逻辑运算符
// ============================================
let userAge = 22
let hasVerifiedEmail = true
let isBanned = false
let isAdmin = false
let isAdult = userAge >= 18
let canAccessSystem = isAdult && hasVerifiedEmail && !isBanned
let hasAdminAccess = isAdmin
let finalAccess = canAccessSystem || hasAdminAccess
print("成年：\(isAdult)")
print("已验证邮箱：\(hasVerifiedEmail)")
print("未被封禁：\(!isBanned)")
print("最终访问权限：\(finalAccess)")

let score = 85
let grade = score >= 60 ? "Pass" : "Fail"
print(grade)  // Pass

var result: String
if score >= 60 {
    result = "Pass"
} else {
    result = "Fail"
}
let result2 = score >= 60 ? "Pass" : "Fail"

let x = 10       // Int
let y = 3.5      // Double
let result1 = Double(x) + y  // 13.5
let result2 = x + Int(y)     // 13（y 被截断为 3）

// ============================================
// 根据购买金额计算折扣
// 演示三元运算符和类型转换
// ============================================
let purchaseAmount = 120.0
let itemCount = 3
let discountRate: Double = purchaseAmount >= 100 ? 0.9 : 1.0
let finalAmount = purchaseAmount * discountRate
let averagePrice = finalAmount / Double(itemCount)
print("购买金额：$\(purchaseAmount)")
print("折扣率：\(Int((1 - discountRate) * 100))%")
print("最终金额：$\(finalAmount)")
print("商品数量：\(itemCount)")
print("件均价格：$\(String(format: "%.2f", averagePrice))")
let freeShipping = finalAmount >= 100 ? "Free Shipping" : "Shipping Fee"
print("运费：\(freeShipping)")

// ============================================
// 月度预算分析工具
// 功能：演示算术、比较、逻辑、三元运算符
// ============================================
import Foundation
// 1. 收入与支出数据
let salary = 5200.0
let rent = 1400.0
let food = 600.0
let transport = 120.0
let utilities = 200.0
let entertainment = 300.0
// 2. 使用算术和复合赋值计算
var totalExpenses = 0.0
totalExpenses += rent
totalExpenses += food
totalExpenses += transport
totalExpenses += utilities
totalExpenses += entertainment
let savings = salary - totalExpenses
let savingsRate = savings / salary * 100
// 3. 使用比较和三元判断财务状况
let isHealthy = savingsRate >= 20
let advice = isHealthy ? "Healthy" : "Needs Improvement"
// 4. 逻辑判断：单项是否超支
let rentTooHigh = rent > salary * 0.3
let foodTooHigh = food > salary * 0.15
let needsAdjustment = rentTooHigh || foodTooHigh
print("=== Monthly Budget ===")
print("Income: $\(salary)")
print("Expenses: $\(totalExpenses)")
print("Savings: $\(String(format: "%.2f", savings))")
print("Savings Rate: \(Int(savingsRate))%")
print("Status: \(advice)")
print("Needs Adjustment: \(needsAdjustment)")
// 5. 类型转换示例
let categoryCount = 5
let avgPerCategory = totalExpenses / Double(categoryCount)
print("Categories: \(categoryCount), Avg: $\(String(format: "%.2f", avgPerCategory))")