CODEWITHSUNDEEP
c#vb.net
SomeNickName
SomeNickName

Reputation: 521

plusequal operator inside if statement

int toAdd = 0;
List<int> list = new List<int> {1500, 1500, 1200, 1200, 1100, 1100, 1100, 1100, 1000, 1000, 900, 900, 600, 600, 600, 600, 400, 400, 400, 400};

for (int i = 0; i < list.Count; i++) 
{
    if ((toAdd += list[i]) <= (3000 - list[i])) 
    {

This c# code works, this vb code doesn't:

Dim toAdd As Integer = 0
Dim list As New List(Of Integer)() From {1500, 1500, 1200, 1200, 1100, 1100, 1100, 1100, 1000, 1000, 900, 900, 600, 600, 600, 600, 400, 400, 400, 400}

For i As Integer = 0 To list.Count - 1
    If (toAdd += list(i)) <= (3000 - list(i)) Then

I've identified the problem being the '+=' operator, if i delete the '=' it magically works.

Does vb.net handle the '+=' differently than c#? I can't understand how am i supposed to do what i'm trying to do inside the if statement in vb.

Upvotes: 1

Views: 124

Answers (3)

Jim Mischel
Jim Mischel

Reputation: 133995

You can't do that in Visual Basic.

In C#, assignments are considered expressions. In VB they're statements, but not expressions. So this statement is valid in C#, but not VB (even when you remove the semicolon):

a = b += 12;  // works in C#, but not in VB

Or, said another way, assignment expressions in C# return a value. In VB, assignment statements do not return a value.

Upvotes: 6

mike
mike

Reputation: 475

This should let you do what you need to do.

Dim toAdd As Integer = 0
Dim list As New List(Of Integer)() From {1500, 1500, 1200, 1200, 1100, 1100, 1100, 1100, 1000, 1000, 900, 900, 600, 600, 600, 600, 400, 400, 400, 400}

For i As Integer = 0 To list.Count - 1
    toAdd = toAdd + list(i)
    If toAdd <= (3000 - list(i)) Then

Upvotes: 4

Kyle W
Kyle W

Reputation: 3752

I don't think VB.Net supports what you're trying to do. Consider x = y = z. It won't evaluate that as set y = z, then set x = y, it will evaluate it as set x equal to the result of whether y is equal to z. I think it expects the += to be an entire statement, and not part of a subexpression. Its the presence inside the if that is screwing it up. Thus, I think the best result is to remove that from the if statement.

For i As Integer = 0 To list.Count - 1
    toAdd = toAdd + list(i)
    If toAdd <= (3000 - list(i)) Then

Upvotes: 1

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