isalpha(c) is a function in C which can be used to check if passed character is an alphabet or not. It returns a non-zero value if it’s an alphabet else it returns 0. For example, it returns non-zero values for ‘a’ to ‘z’ and ‘A’ to ‘Z’ and zero for other characters.
Similarly, isdigit(c) is a function in C which can be used to check if passed character is a digit or not. It returns a non-zero value if it’s a digit else it returns 0. For example, it returns non-zero value for ‘0’ to ‘9’ and zero for others.
Example Problem : Given a string str, find the number of alphabetic letters and number of decimal digits in that string.
Examples:
Input: 12abc12 Output: Alphabetic_letters = 3, Decimal_digits = 4 Input: 123 GeeksForGeeks is Number 1 Output: Alphabetic_letters = 21, Decimal_digits = 4
Explanation And Approach:
// C program to demonstrate working of isalpha() and // isdigit(). #include<stdio.h> #include<stdlib.h> int main() { char str[] = "12abc12" ; int alphabet = 0, number = 0, i; for (i=0; str[i]!= ' |