Method ZipLongest

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ZipLongest<T1, T2, TResult>(IEnumerable<T1>, IEnumerable<T2>, Func<T1?, T2?, TResult>)

Returns a projection of tuples, where each tuple contains the N-th element from each of the argument sequences. The resulting sequence will always be as long as the longest of input sequences where the default value of each of the shorter sequence element types is used for padding.

Declaration
public static IEnumerable<TResult> ZipLongest<T1, T2, TResult>(this IEnumerable<T1> first, IEnumerable<T2> second, Func<T1?, T2?, TResult> resultSelector)
Parameters
Type Name Description
IEnumerable<T1> first

The first sequence of elements.
IEnumerable<T2> second

The second sequence of elements.
Func<T1, T2, TResult> resultSelector

A projection function that combines elements from all of the sequences.
Returns
Type Description
IEnumerable<TResult>

A sequence of elements returned by resultSelector.
Type Parameters
Name Description
T1

The type of the elements of first.
T2

The type of the elements of second.
TResult

The type of the elements of the result sequence.
Remarks

This method uses deferred execution and streams its results.

Examples

The following code example demonstrates how to use the ZipLongest to merge three sequences.

var seq1 = new[] { "aaa", "bb", "c", "ddd", };
var seq2 = new[] { 1, 2, 3, 4, 5 };

// Zip two sequences together
var result = seq1
    .ZipLongest(
        seq2,
        (a, b) => new { A = a, B = b, });

Console.WriteLine(
    "[" +
    string.Join(", ", result) +
    "]");

// This code produces the following output:
// [{ A = aaa, B = 1 }, { A = bb, B = 2 }, { A = c, B = 3 }, { A = ddd, B = 4 }, { A = , B = 5 }]
Exceptions
Type Condition
ArgumentNullException

resultSelector or any of the input sequences is null.
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ZipLongest<T1, T2>(IEnumerable<T1>, IEnumerable<T2>)

Returns a projection of tuples, where each tuple contains the N-th element from each of the argument sequences. The resulting sequence will always be as long as the longest of input sequences where the default value of each of the shorter sequence element types is used for padding.

Declaration
public static IEnumerable<(T1?, T2?)> ZipLongest<T1, T2>(this IEnumerable<T1> first, IEnumerable<T2> second)
Parameters
Type Name Description
IEnumerable<T1> first

The first sequence of elements.
IEnumerable<T2> second

The second sequence of elements.
Returns
Type Description
IEnumerable<(T1, T2)>

A sequence of (T1, T2) containing corresponding elements from each of the sequences.
Type Parameters
Name Description
T1

The type of the elements of first.
T2

The type of the elements of second.
Remarks

This method uses deferred execution and streams its results.

Examples

The following code example demonstrates how to use the ZipLongest to merge two sequences.

var seq1 = new[] { "aaa", "bb", "c", "ddd", };
var seq2 = new[] { 1, 2, 3, 4, 5 };

// Zip two sequences together
var result = seq1.ZipLongest(seq2);

Console.WriteLine(
    "[" +
    string.Join(", ", result) +
    "]");

// This code produces the following output:
// [(aaa, 1), (bb, 2), (c, 3), (ddd, 4), (, 5)]
Exceptions
Type Condition
ArgumentNullException

Any of the input sequences is null.
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ZipLongest<T1, T2, T3, TResult>(IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, Func<T1?, T2?, T3?, TResult>)

Returns a projection of tuples, where each tuple contains the N-th element from each of the argument sequences. The resulting sequence will always be as long as the longest of input sequences where the default value of each of the shorter sequence element types is used for padding.

Declaration
public static IEnumerable<TResult> ZipLongest<T1, T2, T3, TResult>(this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> third, Func<T1?, T2?, T3?, TResult> resultSelector)
Parameters
Type Name Description
IEnumerable<T1> first

The first sequence of elements.
IEnumerable<T2> second

The second sequence of elements.
IEnumerable<T3> third

The third sequence of elements.
Func<T1, T2, T3, TResult> resultSelector

A projection function that combines elements from all of the sequences.
Returns
Type Description
IEnumerable<TResult>

A sequence of elements returned by resultSelector.
Type Parameters
Name Description
T1

The type of the elements of first.
T2

The type of the elements of second.
T3

The type of the elements of third.
TResult

The type of the elements of the result sequence.
Remarks

This method uses deferred execution and streams its results.

Examples

The following code example demonstrates how to use the ZipLongest to merge four sequences.

var seq1 = new[] { "aaa", "bb", "c", };
var seq2 = new[] { 1, 2, 3, 4, };
var seq3 = new[] { 20, 5, 7, 12, 42 };

// Zip three sequences together
var result = seq1
    .ZipLongest(
        seq2,
        seq3,
        (a, b, c) => new { A = a, B = b, C = c, });

Console.WriteLine(
    "[" +
    string.Join(", ", result) +
    "]");

// This code produces the following output:
// [{ A = aaa, B = 1, C = 20 }, { A = bb, B = 2, C = 5 }, { A = c, B = 3, C = 7 }, { A = , B = 4, C = 12 }, { A = , B = 0, C = 42 }]
Exceptions
Type Condition
ArgumentNullException

resultSelector or any of the input sequences is null.
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ZipLongest<T1, T2, T3>(IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>)

Returns a projection of tuples, where each tuple contains the N-th element from each of the argument sequences. The resulting sequence will always be as long as the longest of input sequences where the default value of each of the shorter sequence element types is used for padding.

Declaration
public static IEnumerable<(T1?, T2?, T3?)> ZipLongest<T1, T2, T3>(this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> third)
Parameters
Type Name Description
IEnumerable<T1> first

The first sequence of elements.
IEnumerable<T2> second

The second sequence of elements.
IEnumerable<T3> third

The third sequence of elements.
Returns
Type Description
IEnumerable<(T1, T2, T3)>

A sequence of (T1, T2, T3) containing corresponding elements from each of the sequences.
Type Parameters
Name Description
T1

The type of the elements of first.
T2

The type of the elements of second.
T3

The type of the elements of third.
Remarks

This method uses deferred execution and streams its results.

Examples

The following code example demonstrates how to use the ZipLongest to merge two sequences.

var seq1 = new[] { "aaa", "bb", "c", };
var seq2 = new[] { 1, 2, 3, 4, };
var seq3 = new[] { 20, 5, 7, 12, 42 };

// Zip three sequences together
var result = seq1
    .ZipLongest(
        seq2,
        seq3);

Console.WriteLine(
    "[" +
    string.Join(", ", result) +
    "]");

// This code produces the following output:
// [(aaa, 1, 20), (bb, 2, 5), (c, 3, 7), (, 4, 12), (, 0, 42)]
Exceptions
Type Condition
ArgumentNullException

Any of the input sequences is null.
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ZipLongest<T1, T2, T3, T4, TResult>(IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, IEnumerable<T4>, Func<T1?, T2?, T3?, T4?, TResult>)

Returns a projection of tuples, where each tuple contains the N-th element from each of the argument sequences. The resulting sequence will always be as long as the longest of input sequences where the default value of each of the shorter sequence element types is used for padding.

Declaration
public static IEnumerable<TResult> ZipLongest<T1, T2, T3, T4, TResult>(this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> third, IEnumerable<T4> fourth, Func<T1?, T2?, T3?, T4?, TResult> resultSelector)
Parameters
Type Name Description
IEnumerable<T1> first

The first sequence of elements.
IEnumerable<T2> second

The second sequence of elements.
IEnumerable<T3> third

The third sequence of elements.
IEnumerable<T4> fourth

The fourth sequence of elements.
Func<T1, T2, T3, T4, TResult> resultSelector

A projection function that combines elements from all of the sequences.
Returns
Type Description
IEnumerable<TResult>

A sequence of elements returned by resultSelector.
Type Parameters
Name Description
T1

The type of the elements of first.
T2

The type of the elements of second.
T3

The type of the elements of third.
T4

The type of the elements of fourth.
TResult

The type of the elements of the result sequence.
Remarks

This method uses deferred execution and streams its results.

Examples

The following code example demonstrates how to use the ZipLongest to merge four sequences.

var seq1 = new[] { "aaa", "bb", "c", "ddd", };
var seq2 = new[] { 1, 2, 3, };
var seq3 = new[] { 20, 5, };
var seq4 = new[] { "zz", };

// Zip four sequences together
var result = seq1
    .ZipLongest(
        seq2,
        seq3,
        seq4,
        (a, b, c, d) => new 
        {
            A = a,
            B = b,
            C = c,
            D = d,
        });

Console.WriteLine(
    "[" +
    string.Join(", ", result) +
    "]");

// This code produces the following output:
// [{ A = aaa, B = 1, C = 20, D = zz }, { A = bb, B = 2, C = 5, D =  }, { A = c, B = 3, C = 0, D =  }, { A = ddd, B = 0, C = 0, D =  }]
Exceptions
Type Condition
ArgumentNullException

resultSelector or any of the input sequences is null.
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ZipLongest<T1, T2, T3, T4>(IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, IEnumerable<T4>)

Returns a projection of tuples, where each tuple contains the N-th element from each of the argument sequences. The resulting sequence will always be as long as the longest of input sequences where the default value of each of the shorter sequence element types is used for padding.

Declaration
public static IEnumerable<(T1?, T2?, T3?, T4?)> ZipLongest<T1, T2, T3, T4>(this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> third, IEnumerable<T4> fourth)
Parameters
Type Name Description
IEnumerable<T1> first

The first sequence of elements.
IEnumerable<T2> second

The second sequence of elements.
IEnumerable<T3> third

The third sequence of elements.
IEnumerable<T4> fourth

The fourth sequence of elements.
Returns
Type Description
IEnumerable<(T1, T2, T3, T4)>

A sequence of (T1, T2, T3, T4) containing corresponding elements from each of the sequences.
Type Parameters
Name Description
T1

The type of the elements of first.
T2

The type of the elements of second.
T3

The type of the elements of third.
T4

The type of the elements of fourth.
Remarks

This method uses deferred execution and streams its results.

Examples

The following code example demonstrates how to use the ZipLongest to merge three sequences.

var seq1 = new[] { "aaa", "bb", "c", "ddd", };
var seq2 = new[] { 1, 2, 3, };
var seq3 = new[] { 20, 5, };
var seq4 = new[] { "zz", };

// Zip four sequences together
var result = seq1
    .ZipLongest(
        seq2,
        seq3,
        seq4);

Console.WriteLine(
    "[" +
    string.Join(", ", result) +
    "]");

// This code produces the following output:
// [(aaa, 1, 20, zz), (bb, 2, 5, ), (c, 3, 0, ), (ddd, 0, 0, )]
Exceptions
Type Condition
ArgumentNullException

Any of the input sequences is null.