Strange multiple assignment error in C++

Question

I have multiple assignment statement in my program as shown below where query.constraints.size() is supposed to return 13 (constraints is an array and its returning its size)

int num,size =  query.constraints.size();

When I do this size becomes 13 as expected but num becomes 9790272 for some reason.

When I do them separately as below everything is ok and both of them are 13 as expected

int size =  query.constraints.size();

int num =  query.constraints.size();

Why does my multiple assignment result in a strange a strange value ?

Answer 1

Why does my multiple assignment result in a strange a strange value ?

Because C++ has no multiple assignment¹. You are declaring two variables here, but only initialise the second, not the first.

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¹ Well, you can do int a, b = a = c; but code which does this would be deemed bad by most C++ programmers except in very peculiar circumstances.

Answer 2

You're not assigning multiple times, you're declaring multiple times. You need to do something like:

int num, size;
size = num = query.constraints.size();