Case Changes

The case change commands described here work on text in the current buffer. See Case Conversion, for case conversion functions that work on strings and characters. See Case Tables, for how to customize which characters are upper or lower case and how to convert them.

— Command: capitalize-region start end

This function capitalizes all words in the region defined by start and end. To capitalize means to convert each word's first character to upper case and convert the rest of each word to lower case. The function returns nil.
If one end of the region is in the middle of a word, the part of the word within the region is treated as an entire word.
When capitalize-region is called interactively, start and end are point and the mark, with the smallest first.
          ---------- Buffer: foo ----------
          This is the contents of the 5th foo.
          ---------- Buffer: foo ----------
          
          (capitalize-region 1 37)
          ⇒ nil
          
          ---------- Buffer: foo ----------
          This Is The Contents Of The 5th Foo.
          ---------- Buffer: foo ----------

— Command: downcase-region start end

This function converts all of the letters in the region defined by start and end to lower case. The function returns nil.
When downcase-region is called interactively, start and end are point and the mark, with the smallest first.

— Command: upcase-region start end

This function converts all of the letters in the region defined by start and end to upper case. The function returns nil.
When upcase-region is called interactively, start and end are point and the mark, with the smallest first.

— Command: capitalize-word count

This function capitalizes count words after point, moving point over as it does. To capitalize means to convert each word's first character to upper case and convert the rest of each word to lower case. If count is negative, the function capitalizes the −count previous words but does not move point. The value is nil.
If point is in the middle of a word, the part of the word before point is ignored when moving forward. The rest is treated as an entire word.
When capitalize-word is called interactively, count is set to the numeric prefix argument.

— Command: downcase-word count

This function converts the count words after point to all lower case, moving point over as it does. If count is negative, it converts the −count previous words but does not move point. The value is nil.
When downcase-word is called interactively, count is set to the numeric prefix argument.

— Command: upcase-word count

This function converts the count words after point to all upper case, moving point over as it does. If count is negative, it converts the −count previous words but does not move point. The value is nil.
When upcase-word is called interactively, count is set to the numeric prefix argument.

32.18 Case Changes