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Ruby Upcase, downcase String ExamplesUppercase and lowercase a string with the upcase and downcase methods. Change a string in-place.
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Upcase, downcase. The upcase() and downcase() methods affect letters. Upcase changes lowercase letters to uppercase. And downcase changes uppercase letters to lowercase.
Notes, assignment. You must assign to the result of upcase() and downcase(). The original string instance is not modified—a modified copy of the string is made.
First example. We begin by calling the upcase method, and then invoking the downcase method on the result. When we call these methods, only letters are affected.
Info Numbers and spaces are not affected or removed by upcase and downcase—they are left alone in the string.
Ruby program that uses upcase, downcase
# An input string. value = "BLUE bird" # Change cases. upper = value.upcase() lower = value.downcase() # Display results. puts upper puts lower
BLUE BIRD blue bird
In-place. Suppose we want to modify a string in-place, without having to assign the result of upcase or downcase. We can use an exclamation mark to modify the current string variable.
Ruby program that uses upcase in-place
test = "bird" # Use exclamation mark to modify the string in-place. test.upcase! puts test
BIRD
A summary. In Ruby, we sometimes have logic that preprocesses files containing data that may have inconsistent cases. Often we want to lowercase (or uppercase) every string we encounter.
File, IO
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