In this guide, you will learn what is islower() function is in C++ programming and how to use it with an example.
1. islower() Function Overview
The islower() function is part of the C++ <cctype> library. It checks if the given character is a lowercase alphabetic letter (a-z).
Signature:
int islower(int ch);
Parameters:
- ch: The character to be checked. Although it's an int, it essentially represents the ASCII value of the character.
2. Source Code Example
#include <iostream>
#include <cctype>
int main() {
char ch1 = 'g';
char ch2 = 'M';
if(islower(ch1)) {
std::cout << "ch1 is a lowercase alphabetic letter." << std::endl;
} else {
std::cout << "ch1 is not a lowercase alphabetic letter." << std::endl;
}
if(islower(ch2)) {
std::cout << "ch2 is a lowercase alphabetic letter." << std::endl;
} else {
std::cout << "ch2 is not a lowercase alphabetic letter." << std::endl;
}
return 0;
}
Output:
ch1 is a lowercase alphabetic letter. ch2 is not a lowercase alphabetic letter.
3. Explanation
In this example, the islower() function is used to determine whether a character is a lowercase letter.
The character 'g' is lowercase, so for ch1, the function returns true.
On the other hand, ch2 contains the uppercase character 'M', hence for ch2, it returns false.
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