In C++, isupper() and islower() are predefined functions used for string and character handling.cstring.h is the header file required for string functions and cctype.h is the headerfile required for character functions.
This function is used to check if the arguement contains any uppercase letters such as A, B, C, D……….Z.
Syntax int isupper(int x)
Input : A Output : Uppercase
Input : a Output : Not uppercase
This function is used to check if the arguement contains lowercase letters such as a, b, c, d, ……..z.
Syntax int islower(int x)
Input:A Output : Not Lowercase
Input : a Output : Lowercase
Application of islower(), isupper(), tolower(), toupper() function.
Given a string, task is to convert the characters in the string into opposite case, i.e. if a character is in lowercase, we need to convert it into uppercade and vice versa.
Input : GeekS Output :gEEKs Input :Test Case Output :tEST cASE
1. Traverse the given string character by character upto its length, check if character is in lowercase or uppercase using predefined function.
3. If lowercase, convert it to uppercase using toupper() function, if uppercase, convert it to lowercase using tolower() function.
4. Print the final string.
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