關於「C toupper」標籤，搜尋引擎有相關的訊息討論：

Converting char * to Uppercase in C - string - Stack Overflowstackoverflow.com › questions › converting-char-to-upper...C library function - toupper() - Tutorialspointwww.tutorialspoint.com › c_standard_library › c_function...C 語言標準函數庫分類導覽- ctype.h toupper()pydoing.blogspot.com