variable-assignment

I have an HTML page with the following JavaScript attached. alert(box); box = "Thinking outside the box"; In the console I get "Uncaught ReferenceError: box is not defined" when I change it to: alert(box); var box = "Thinking outside the box"; The alert gets called and shows undefined. I need to be able to explain this, I have a vague idea of why this happens. I know that when I use var, JavaScript knows the variable is there before the alert is executed, but has not necessarily assigned a value to it?? Am I way off here? Need some help understanding this. jfriend00 When you define a variable

I know in some languages the following: a += b is more efficient than: a = a + b because it removes the need for creating a temporary variable. Is this the case in C? Is it more efficient to use += (and, therefore also -= *= etc) So here's a definitive answer... $ cat junk1.c #include <stdio.h> int main() { long a, s = 0; for (a = 0; a < 1000000000; a++) { s = s + a * a; } printf("Final sum: %ld\n", s); } michael@isolde:~/junk$ cat junk2.c #include <stdio.h> int main() { long a, s = 0; for (a = 0; a < 1000000000; a++) { s += a * a; } printf("Final sum: %ld\n", s); } michael@isolde:~/junk$ for

$a = $b = 0; In the above code, are both $a and $b assigned the value of 0 , or is $a just referencing $b ? With raw types this is a copy. test.php $a = $b = 0; $b = 3; var_dump($a); var_dump($b); Output : int(0) int(3) With objects though, that is another story (PHP 5) test.php class Obj { public $_name; } $a = $b = new Obj(); $b->_name = 'steve'; var_dump($a); var_dump($b); Output object(Obj)#1 (1) { ["_name"]=> string(5) "steve" } object(Obj)#1 (1) { ["_name"]=> string(5) "steve" } Regard this code as: $a = ($b = 0); The expression $b = 0 not only assigns 0 to $b , but it yields a result as

I was unable to find any reference to this in the documentations... Is assigning to a double (or any other simple type, including boolean) an atomic operation viewed from the perspective of threads? double value = 0; public void First() { while(true) { value = (new Random()).NextDouble(); } } public void Second() { while(true) { Console.WriteLine(value); } } In this code sample, first method is called in one thread, and the second in another. Can the second method get a messed up value if it gets its execution during assignment to the variable in another thread? I don't care if I receive the

I'm using this code which has an error: SET @rejects = ''; SELECT * FROM list WHERE maker = 1 AND by_ids IN ('10','11') AND country LIKE '%I%' AND ( src IS NULL || src NOT IN (@rejects) AND checkSrc(src) = 'yes' AND SET @rejects = CONCAT(@rejects,',',src) ); What's causing the issue? The issue is that you cannot mix select and set in one statement, there'll surely be syntax error: select*from t where 1 and set@a=1; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'set@a=1' at line 1 If you

I wrote a C program as follows: CASE 1 int *a; /* pointer variable declaration */ int b; /* actual variable declaration */ *a=11; a=&b;/* store address of b in pointer variable*/ It gives a segmentation fault when running the program. I changed the code as follows: CASE 2 int *a; /* pointer variable declaration */ int b; /* actual variable declaration */ a=&b;/* store address of b in pointer variable*/ *a=11; Now it's working fine. If anyone knows please explain why it is giving a segmentation fault in CASE 1. CASE .1 int *a; /* pointer variable declaration */ int b; /* actual variable

How can I do the following in tensorflow? mat = [4,2,6,2,3] # mat[2] = 0 # simple zero the 3rd element I can't use the [] brackets because it only works on constants and not on variables. I cant use the slice function either because that returns a tensor and you can't assign to a tensor. import tensorflow as tf sess = tf.Session() var1 = tf.Variable(initial_value=[2, 5, -4, 0]) assignZerosOP = (var1[2] = 0) # < ------ This is what I want to do sess.run(tf.initialize_all_variables()) print sess.run(var1) sess.run(assignZerosOP) print sess.run(var1) Will print [2, 5, -4, 0] [2, 5, 0, 0]) dga You