zero

I need to perform an avg on a column, but I know that most of the values in that column will be zero. Out of all possible rows, only two will probably have positive values. How can I tell mySQL to ignore the zeros and only average the actual values? Assuming that you might want to not totally exclude such rows (perhaps they have values in other columns you want to aggregate) SELECT AVG(NULLIF(field ,0)) from table You could probably control that via the WHERE clause: select avg( field ) from table where field > 0 select avg(your_column) from your_table where your_column != 0 Barvajz You can

This question already has an answer here: Comparing numbers in Bash 8 answers I have a bash variable depth and I would like to test if it equals 0. In case yes, I want to stop executing of script. So far I have: zero=0; if [ $depth -eq $zero ]; then echo "false"; exit; fi Unfortunately, this leads to: [: -eq: unary operator expected (might be a bit inaccurate due to translation) Please, how can I modify my script to get it working? Looks like your depth variable is unset. This means that the expression [ $depth -eq $zero ] becomes [ -eq 0 ] after bash substitutes the values of the variables

I want to repeatedly zero a large 2d array in C. This is what I do at the moment: // Array of size n * m, where n may not equal m for(j = 0; j < n; j++) { for(i = 0; i < m; i++) { array[i][j] = 0; } } I've tried using memset: memset(array, 0, sizeof(array)) But this only works for 1D arrays. When I printf the contents of the 2D array, the first row is zeroes, but then I got a load of random large numbers and it crashes. memset(array, 0, sizeof(array[0][0]) * m * n); Where m and n are the width and height of the two-dimensional array (in your example, you have a square two-dimensional array, so

I'm trying to send a large file through readfile() . However, nothing is sent to the browser and readfile() returns 0 ( not false !). The file I'm trying to send is 4GiB of size and readable by PHP. I am setting set_time_limit(0) to allow a lengthy download process. I have tried to send the file in a while-loop contraption with fread() in 4K chunks and echo , but that aborts randomly (without error) after 500 - 2500 MiB downloaded and never manages to complete the download. The following test code $f = '/var/www/tmp/largefile.dat'; var_dump(file_exists($f)); var_dump(is_readable($f)); var_dump

the code: Float f = Float.parseFloat("1.80"); System.out.println(f); prints "1.8" on screen. I need to keep the 0 in the float value (Float f) for some validation. How do I do this? You are confusing a number value and its formatting . It is not possible to actually store 1.80 as a float, however it is possible to display the number as a formatted String which forces two decimal places. Your options are: Keep the original String that the user entered, if the number of decimal places they gave matters Store the number as a float , but when displaying the number force it to display with two

I've learned that floating point number s have a signed zero in java. But I'm afraid Integer has not: new Integer("0").equals(new Integer("-0")) // true vs. new Double("0").equals(new Double("-0")) // false How could I store a sign with my zero Integer value? You cannot store a sign with Java integer primitive type. Negative zero is an artifact of IEEE-754 representation, which stores a sign in a separate bit. Integers, on the other hand, are stored in two's complement representation, which has a unique representation for zero. 来源： https://stackoverflow.com/questions/41893756/is-there-a-signed

Can I check in C(++) if an array is all 0 (or false) without iterating/looping over every single value and without allocating a new array of the same size (to use memcmp )? I'm abusing an array of bools to have arbitrary large bitsets at runtime and do some bitflipping on it You can use the following condition: (myvector.end() == std::find(myvector.begin(), myvector.end(), true)) Obviously, internally, this loops over all values. The alternative (which really should avoid looping) is to override all write-access functions, and keep track of whether true has ever been written to your vector.

Is there a way to initialize an array of primitives, say a integer array, to 0? Without using a for loop? Looking for concise code that doesn't involve a for loop. :) int array[10] = {}; // to 0 std::fill(array, array + 10, x); // to x Note if you want a more generic way to get the end: template <typename T, size_t N> T* endof(T (&pArray)[N]) { return &pArray[0] + N; } To get: std::fill(array, endof(array), x); // to x (no explicit size) It should be mentioned std::fill is just a wrapper around the loop you're trying to avoid, and = {}; might be implemented in such terms. Yes, it is possible.