This is probably a silly question, but curiosity has gotten the better of me. I've been seeing code lately that seems to "reverse" the order of expressions for relational operators e.g.: if (0 == someVariable) As opposed to what I normally see/write: if (someVariable == 0) To me, the second method seems more readable and intuitive,...
I'm working with Ruby on Rails and would like to validate two different models : if (model1.valid? && model2.valid?) ... end However, "&&" operator uses short-circuit evaluation (i.e. it evaluates "model2.valid?" only if "model1.valid?" is true), which prevents model2.valids to be executed if model1 is not valid. Is there an equivale...
SELECT item_name from items WHERE item_id = $var; I tried: $var = 001 || 002 || 003 || 004; $var = 001 OR 002 OR 003 OR 004; $var = 001 or 002 or 003 or 004; But all do not work. Thanks, i try that, but the output only 1 result => 1. What I want is to output all, i.e. 1, 2 , 3 and 4.. Means, I want to select multiple records(rows...
Ok, so I've read about this a number of times, but I'm yet to hear a clear, easy to understand (and memorable) way to learn the difference between: if (x | y) and if (x || y) ..within the context of C#. Can anyone please help me learn this basic truth, and how C# specifically, treats them differently (because they seem to do the ...
Can I achieve if(a == "b" || "c") instead of if(a == "b" || a== "c") ...
Why doesn't func3 get executed in the program below? After func1, func2 doesn't need to get evaluated but for func3, shouldn't it? if (func1() || func2() && func3()) { System.out.println("true"); } else { System.out.println("false"); } } public static boolean func1() { System.out.println("func1"); return...
Hello all, I searched the site but did not find the answer I was looking for so here is a really quick question. I am trying to do something like that : #ifdef _WIN32 || _WIN64 #include <conio.h> #endif How can I do such a thing? I know that _WIN32 is defined for both 32 and 64 bit windows so I would be okay with just it for win...
Hello all, I have a simple question that I am posing mostly for my curiousity. What are the differences between these two lines of code? (in C++) for(int i = 0; i < N, N > 0; i++) for(int i = 0; i < N && N > 0; i++) The selection of the conditions is completely arbitrary, I'm just interested in the differences between , and &&. I'm...
In other programming languages (Python, Ruby, Scheme), I'm used to doing things like $foo = $cat && $dog; $bar = $fruit || $vegetable; I would expect that $foo would get assigned to $dog if $cat were null, and $bar to $fruit if $fruit were NOT null. I seem to recall getting burned for doing things like this in PHP, and I've never lear...
I don't understand the following excerpt from Accelerated C++: Starting at Because || is left-associative, and because of the relative precedence of ||,== ,and -, r == 0 || r == rows - 1 || c == 0 || c == cols - 1 means the same as it would if we were to place all of its subexpressions in parentheses: ((r == 0 |...
Everyone here should know the 'or' statemens, usually glued to an die() command: $foo = bar() or die('Error: bar function return false.'); The most of the times we see something like: mysql_query('SELECT ...') or die('Error in during the query'); However, i cant understand how exactly that 'or' statement works. I would like to thr...
Are the two statements below equivalent? SELECT [...] FROM [...] WHERE some_col in (1,2,3,4,5) AND some_other_expr and SELECT [...] FROM [...] WHERE some_col in (1,2,3) or some_col in (4,5) AND some_other_expr Is there some sort of truth table I could use to verify this? Thanks. ...
What is the difference between the & and && logical operators in MATLAB? ...
I wonder why ruby give and, or less precedence than &&, || , and assign operator? Is there any reason? ...
tl;dr: Is there a non-short circuit logical AND in C++ (similar to &&)? I've got 2 functions that I want to call, and use the return values to figure out the return value of a 3rd composite function. The issue is that I always want both functions to evaluate (as they output log information about the state of the system) IE: bool Func...
I thought Java had short circuit evaluation, yet this line is still throwing a null pointer exception: if( (perfectAgent != null) && (perfectAgent.getAddress().equals(entry.getKey())) ) { In this case perfectAgent is null, so I just want the whole expression to return false, but my app is still crashing on this line with a NullPointer...
while (curr_data[1] != (unsigned int)NULL && ((curr_ptr = (void*)curr_data[1]) || 1)) Two part question. What will (curr_ptr = (void*)curr_data[1]) evaluate to, logically. TRUE? Also, I know its rather hack-ish, but is the while statement legal C? I would have to go through great contortions to put the assignment elsewhere in the...
This is going to be a "long one". I'm including as much code and explanation as possible ... I'm not above throwing out code if necessary. I'm trying to implement a logical parser in a django query system. Where users can provide complex queries against tags that are applied to samples. This is essentially part of a scientific sample...
(myVar && foo()) what does the above code mean? what is it equivalent to? this is an inline code i think it runs on a single line ...
Which order is the and && operator evaluated For example the following code if (int alpha = value1-value2 && alpha > 0.001) //do something threw an exception that alpha is being used without being initiated. I thought the expression left of the && would always initiate the value of alpha first, but it seems I may be wrong Any id...