大数据（7c）比较Python和Scala的流程控制

Posted 2021-05-22 小基基o_O

以Python为参照，理解和速查Scala语法

• 判断：if else
• 循环：for
• 循环：do while
• 循环+break
• 循环+continue
• 模式匹配
• 补充：

判断：if else

if a > 9:
    print(9)
elif a > 5:
    print(5)
else:
    print('python')

if (a > 9) {
  print(9)
}
else if (a > 5) {
  print(5)
}
else {
  print("scala")
}

循环：for

for i in range(5, 0, -2):
    for j in range(i):
        print(i, j)

for (i <- 5 to 1 by -2) {
  for (j <- 0 until i) {
    println(i, j)
  }
}

循环：do while

a = 9
print(a)
a -= 1
while a > 6:
    print(a)
    a -= 1

var a = 9
do {
  print(a)
  a -= 1
} while (a > 6)

循环+break

a = 9
while True:
    a -= 1
    if a < 5:
        break
    print(a)

breakable套在while上

var a = 9
import util.control.Breaks.{breakable,break}
breakable {
  while (true) {
    a -= 1
    if (a < 5) {
      break
    }
    println(a)
  }
}

循环+continue

for i in range(9):
    if i % 2 == 1:
        continue
    print(i)

breakable套在if上

import scala.util.control.Breaks.{break, breakable}
for (i <- 0 until 9)
  breakable {
    if (i % 2 == 1) {
      break()
    }
    print(i)
  }

模式匹配

https://yellow520.blog.csdn.net/article/details/113100081

补充：

Scala的if else表达式是有返回值

var age = 19
var a = if(age > 18){
  "大个仔啦"
}else{
  "小屁孩"
}
println(a)