casefold
Usage
casefold(x, upper = FALSE)
大小寫轉(zhuǎn)換
Arguments
upper→邏輯值,是否轉(zhuǎn)換為大寫,默認(rèn)為FALSE
Example

casefold用法
tolower&toupper
Usage
tolower(x)→轉(zhuǎn)換為小寫
toupper(x)→轉(zhuǎn)換為大寫
Example

tolower&toupper用法
推論inference
From above examples,we can know that:
toupper(x) = casefold(x,upper = T)