# isalpha() and isdigit() functions in C/C++ with example

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
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Explanation And Approach:

 `// C program to demonstrate working of isalpha() and ` `// isdigit(). ` `#include ` `#include ` ` `  `int` `main() ` `{ ` `    ``char` `str[] = ``"12abc12"``; ` ` `  `    ``int` `alphabet = 0, number = 0, i; ` `    ``for` `(i=0; str[i]!= ``''``; i++) ` `    ``{ ` `        ``// check for alphabets ` `        ``if` `(``isalpha``(str[i]) != 0) ` `            ``alphabet++; ` ` `  `        ``// check for decimal digits ` `        ``else` `if` `(``isdigit``(str[i]) != 0) ` `            ``number++; ` `    ``} ` ` `  `    ``printf``(``"Alphabetic_letters = %d, "` `           ````"Decimal_digits = %d "````, alphabet, number); ` ` `  `    ``return` `0; ` `} `

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Output:

```Alphabetic_letters = 3, Decimal_digits = 4
```

## tags:

C C++ C-Library CPP-Library C CPP