How to Check if String contains only Alphabets and Numbers in C - Step by Step Examples

How to Check if String contains only Alphabets and Numbers in C ?

Answer

To check if a string contains only alphabets and numbers in C, you can use the isalpha and isdigit functions from the ctype.h library.

✐ Examples

1 Check if String Contains Only Alphabets and Numbers

In this example,

We include the necessary headers stdio.h for standard input/output functions and ctype.h for character handling functions.
We create a character array named str with a string value.
We initialize a variable is_alnum to 1 (true).
The loop iterates over each character in the string using a for loop.
In each iteration, we check if the current character is either an alphabet or a digit using the isalpha and isdigit functions.
If any character is neither an alphabet nor a digit, we set is_alnum to 0 (false) and break out of the loop.
After the loop, we print whether the string contains only alphabets and numbers based on the value of is_alnum.

C Program

#include <stdio.h>
#include <ctype.h>

int main() {
    char str[] = "Hello123";
    int is_alnum = 1;

    for (int i = 0; str[i] != '\0'; i++) {
        if (!isalpha(str[i]) && !isdigit(str[i])) {
            is_alnum = 0;
            break;
        }
    }

    if (is_alnum) {
        printf("The string contains only alphabets and numbers.\n");
    } else {
        printf("The string contains non-alphanumeric characters.\n");
    }

    return 0;
}

Output

The string contains only alphabets and numbers.

2 Check if Another String Contains Only Alphabets and Numbers

In this example,

We include the necessary headers stdio.h for standard input/output functions and ctype.h for character handling functions.
We create a character array named str with a different string value.
We initialize a variable is_alnum to 1 (true).
The loop iterates over each character in the string using a for loop.
In each iteration, we check if the current character is either an alphabet or a digit using the isalpha and isdigit functions.
If any character is neither an alphabet nor a digit, we set is_alnum to 0 (false) and break out of the loop.
After the loop, we print whether the string contains only alphabets and numbers based on the value of is_alnum.

C Program

#include <stdio.h>
#include <ctype.h>

int main() {
    char str[] = "Hello@123";
    int is_alnum = 1;

    for (int i = 0; str[i] != '\0'; i++) {
        if (!isalpha(str[i]) && !isdigit(str[i])) {
            is_alnum = 0;
            break;
        }
    }

    if (is_alnum) {
        printf("The string contains only alphabets and numbers.\n");
    } else {
        printf("The string contains non-alphanumeric characters.\n");
    }

    return 0;
}

Output

The string contains non-alphanumeric characters.

Summary

In this tutorial, we learned How to Check if String contains only Alphabets and Numbers in C language with well detailed examples.

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How to Check if String contains only Alphabets and Numbers in C - Step by Step Examples

How to Check if String contains only Alphabets and Numbers in C ?

Answer

✐ Examples

1 Check if String Contains Only Alphabets and Numbers

C Program

Output

2 Check if Another String Contains Only Alphabets and Numbers

C Program

Output

Summary

More C Strings Tutorials