substr(“Hello,张三丰”,6,6) 的函数值是?
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Stata 函数大全答:substr(s,n1,n2) 返回s1的子集,从s1中第n1个字符开始抽取,抽n2个字符 例如: substr("abcdef",2,3) = "bcd" substr("abcdef",-3,2) = "de" substr("abcdef",2,.) = "bcdef" substr("abcdef",-3,.) = "def" substr("abcdef",2,0) = "" substr("abcdef",15,2) = "" trim(s)...