It returns a single character string. It is the shortest way to write a single-character string literal. Use it when you want to define a lot of single-character strings. It is a heritage from Ruby <1.9, where it used to return the ASCII code for that character. I don’t understand what you mean by “break … Read more
In MySQL, := is an assignment operator: SELECT @foo := ‘bar’; // variable ‘foo’ now has value ‘bar’ return value: ‘bar’ while = is an equality test: SELECT @foo = ‘hi mom’; // does variable ‘foo’ have the value ‘hi mom’; return value: false (‘bar’ == ‘hi mom’ -> false) Note that you CAN do … Read more
Neither /\ nor / are defined as operators in the ISO C89 standard, and I don’t think they were ever defined in any earlier version. And they are definitely not defined in C99 as far as I know. Here’s a draft of the ANSI C89 standard, for reference: http://flash-gordon.me.uk/ansi.c.txt (You are likely a victim of … Read more
Compare the binary representations of each of those. 110 & 010 = 010 1010 & 0101 = 0000 10100 & 11001 = 10000 1111011 & 0010100 = 0010000 In each case, a digit is 1 in the result only when it is 1 on both the left AND right side of the input.
In a declaration, it means it’s a pointer to a pointer: int **x; // declare x as a pointer to a pointer to an int When using it, it deferences it twice: int x = 1; int *y = &x; // declare y as a pointer to x int **z = &y; // declare z … Read more
It’s the right bit shift operator, ‘moves’ all bits once to the right. 10 in binary is 1010 shifted to the right it turns to 0101 which is 5
That is because a[index++] = index = index + 2; invokes Undefined Behavior in C. Have a look at this From the link: ..the second sentence says: if an object is written to within a full expression, any and all accesses to it within the same expression must be directly involved in the computation of … Read more
Let’s use 16 bits for our example. In that case, ~0 is equal to 1111111111111111 When we left-shift this n bits (3 in your case), we get: 1111111111111000 because the 1s at the left are discarded and 0s are fed in at the right. Then re-complementing it gives: 0000000000000111 so it’s just a clever way … Read more
Yes, you’re exactly right. Here you have two equality checks, which have the same operator precedence. First one evaluates first, then its result applies to the next equality check. 1===1===1is the same as (1===1)===1 which is true===1 which is false, because here you check by values AND their types. 1==1==1 will result in true, because … Read more