int main() {
    char userString[100];
    userInputString(userString);


    return 0;
}


int userInputString(char userString[]) {
    printf("Please enter 100 characters or less: \n");

    scanf("%s", userString);
    if ((userString <= 'a' && userString >= 'z') || (userString <= 'A' && userString >= 'Z')) {
        printf("\n%s\n", userString);
        PAUSE;
    }
    else {
        printf("Invalid input. You may only enter alphabetical characters. \n");
        PAUSE;
    }
}

I want to validate the user input so the user inputted string only contains alphabetical characters. When I run this however, it will say invalid input. Thank you for any help provided!