Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
ForAll Method (Int32, Int32, Predicate(Int32))

Contract.ForAll Method (Int32, Int32, Predicate<Int32>)

Determines whether a particular condition is valid for all integers in a specified range.

Namespace:  System.Diagnostics.Contracts
Assemblies:   mscorlib (in mscorlib.dll)
  System.Diagnostics.Contracts (in System.Diagnostics.Contracts.dll)

public static bool ForAll(
	int fromInclusive,
	int toExclusive,
	Predicate<int> predicate
)

Parameters

fromInclusive
Type: System.Int32

The first integer to pass to predicate.

toExclusive
Type: System.Int32

One more than the last integer to pass to predicate.

predicate
Type: System.Predicate<Int32>

The function to evaluate for the existence of the integers in the specified range.

Return Value

Type: System.Boolean
true if predicate returns true for all integers starting from fromInclusive to toExclusive - 1.

ExceptionCondition
ArgumentNullException

predicate is null.

ArgumentException

toExclusive is less than fromInclusive.

The toExclusive parameter is one more than the last integer to facilitate using the length of a range of integers starting at 0. For example, it would be set to 5 for integers 0 through 4.

The following example demonstrates how to use the ForAll method to determine whether an array has a null element.

using System;
using System.Diagnostics.Contracts;
using System.Collections.Generic;
namespace AssumeEx
{
    class Program
    {
        // Start application with at least two arguments 
        static void Main(string[] args)
        {
            args[1] = null;
            Contract.Requires(args != null && Contract.ForAll(0, args.Length, i => args[i] != null));
            // test the ForAll method.  This is only for purpose of demonstrating how ForAll works.
            CheckIndexes(args);
            Stack<string> numbers = new Stack<string>();
            numbers.Push("one");
            numbers.Push("two");
            numbers.Push(null);
            numbers.Push("four");
            numbers.Push("five");
            Contract.Requires(numbers != null && !Contract.ForAll(numbers, (String x) => x != null));
            // test the ForAll generic overload.  This is only for purpose of demonstrating how ForAll works.
            CheckTypeArray(numbers);
        }

        private static bool CheckIndexes(string[] args)
        {
            try
            {
                if (args != null && !Contract.ForAll(0, args.Length, i => args[i] != null))
                    throw new ArgumentException("The parameter array has a null element", "args");
                return true;
            }
            catch (ArgumentException e)
            {
                Console.WriteLine(e.Message);
                return false;
            }
        }
        private static bool CheckTypeArray(IEnumerable<String> xs)
        {
            try
            {
                if (xs != null && !Contract.ForAll(xs, (String x) => x != null))
                    throw new ArgumentException("The parameter array has a null element", "indexes");
                return true;
            }
            catch (ArgumentException e)
            {
                Console.WriteLine(e.Message);
                return false;
            }
        }
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
Show:
© 2015 Microsoft