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...