perfrom循环专门设计COBOL语言
COBOL语言
发布：1959年
作者：葛丽丝·穆雷·霍普
perfrom有四种类型：
❶perfrom until
❷perfrom varying
❸perfrom times
❹perfrom thru/through
注：Visual COBOL增加了perfrom遍历
perfrperfrom until(直到循环)
perform until i>5
add 1 to i
end-perfrom
perfrom varying(迭代因子)
perfrom varying i from 1 by 1 until i>5
end-perfrom
注：设置步长，迭代因子不需要手动赋值累加i，而自动i加1(取决步长)
perfrom times(循环次数)
perfrom 5 times
end-perfrom
perfrom thru(执行段落)
perfrom a-routine thru z-routine
a-routine.
display 'Hello World'.
z-routone.
Visual COBOL
set content of v to ("AB","CD")
perform varying e as string through v
display e
end-perform
