Check string null in any better way C#

In case any null will be a false for you:

bool CheckAnyNull(params string[] strs)
{
    foreach (var str in strs)
    {
        if (strs.IsNullOrWhiteSpace(str))
            return true;
    }

    return false;
}

If you want to check if they are all null:

bool CheckAllNull(params string[] strs)
{
    foreach (var str in strs)
    {
        if (!strs.IsNullOrWhiteSpace(str))
            return false;
    }

    return true;
}

If you want a specific amount of null strings:

int CheckNullCount(params string[] strs)
{
    int count;
    foreach (var str in strs)
    {
        if (strs.IsNullOrWhiteSpace(str))
            count++;
    }

    return count;
}

All of them can then be called like this:

CheckAnyNulls(str1, str2, str3, str4, str5, str6, str7);
CheckAllNulls(str1, str2, str3, str4, str5, str6, str7);
int nullStrs = CheckNullCount(str1, str2, str3, str4, str5, str6, str7);

or:

var strs = new string[7];
// populate the strs array.
CheckAnyNulls(strs);
CheckAllNulls(strs);
int nullStrs = CheckNullCount(strs);

If you are looking to return whatever one of the strings isn't empty, than this is a nice solution:

public static bool AreAllStringsEmpty(params string[] array)
{
    return array.All(str => String.IsNullOrWhiteSpace(str));
}

public static bool AreAllStringsFull(params string[] array)
{
    return array.All(str => !String.IsNullOrWhiteSpace(str));
}

public static bool AreAtleastOneStringFull(params string[] array)
{
    return array.Any(str => !String.IsNullOrWhiteSpace(str));
}

And than use it like this:

AreAllStringsFull(param1, param2, ...);

Remark: You can add extension method to simplify the process, but it's still boilerplate code.

If you don't need to check for whitespace just compare to null:

if (param1 != null)

Conventionally, if the input is required to be not null you would throw an ArgumentNullException:

if (param1 == null)
   throw new ArgumentNullException("param1");

You can build an extension method using reflection to check your entire object at once. However, since this gets expensive, you can use a library such as FastMember to minimize the reflection cost on subsequent object checks.

using System.Linq;
using FastMember;

namespace Utilities
{
    public static class CheckStringProperties
    {
        public static bool AreAnyStringPropertiesNull<T>(this T model) where T : class
        {
            var accessor = TypeAccessor.Create(model.GetType());
            return AreAnyStringPropertiesNull(model, accessor);
        }

        public static bool AreAnyStringPropertiesNull<T>(this T model) where T : class
        {
            var accessor = TypeAccessor.Create(model.GetType());
            return AreAllStringPropertiesNull(model, accessor);
        }

        private static bool AreAnyStringPropertiesNull<T>(T model, TypeAccessor accessor)
        {
            foreach (var strng in GetStringProperties(accessor))
            {
                if (string.IsNullOrWhiteSpace(strng))
                    return true;
            }

            return false;
        }

        private static bool AreAllStringPropertiesNull<T>(T model, TypeAccessor accessor)
        {
            foreach (var strng in GetStringProperties(accessor))
            {
                if (!string.IsNullOrWhiteSpace(strng))
                    return true;
            }

            return false;
        }

        private static List<Member> GetStringProperties(TypeAccessor accessor)
        {
            return accessor.GetMembers().Where(x => x.Type == typeof(string)).ToList();
        }
    }
}

You can then just call the extension method on your class.

var containsNulls = classInstance.AreAnyStringPropertiesNull();
var areAllNull = classInstance.AreAllStringPropertiesNull();