使用 stride(from:to:by:) 计数

为何需要步进

for n in stride(from: 0, to: 10, by: 2) {
    print(n)
}

步进函数的起点、终点和步长

for n in stride(from: 0, to: 5, by: 1) {
    print(n)
}

步进函数的起点、终点和步长（包含终点）

for n in stride(from: 0, through: 10, by: 5) {
    print(n)
}

向下计数

for n in stride(from: 5, through: 1, by: -1) {
    print(n)
}

跳过值

for n in stride(from: 0, to: 20, by: 5) {
    print(n)
}

使用双精度值进行步进

for x in stride(from: 0.0, through: 1.0, by: 0.25) {
    print(x)
}

独占式与包含式的区别

print(Array(stride(from: 1, to: 4, by: 1)))
print(Array(stride(from: 1, through: 4, by: 1)))

将步进结果放入数组

let evens = Array(stride(from: 0, through: 10, by: 2))
print(evens)

使用步进进行索引

let items = ["a", "b", "c", "d", "e"]
for i in stride(from: 0, to: items.count, by: 2) {
    print(items[i])
}

反向迭代

let nums = [10, 20, 30]
for i in stride(from: nums.count - 1, through: 0, by: -1) {
    print(nums[i])
}

对步进结果求和

var total = 0
for n in stride(from: 0, through: 100, by: 10) {
    total += n
}
print(total)

快速检查

回顾：使用步进计数

for n in stride(from: 0, through: 6, by: 2) { print(n) }