Today I had a weird one.

The PHP function named stream_socket_client(), used to create a socket to communicate with another computer over a network, may return $errno = 0 and $errstr = "".

The PHP reference actually mentions the problem:

On failure the errno and errstr arguments will be populated with the actual system level error that occurred in the system-level connect() call. If the value returned in errno is 0 and the function returned FALSE, it is an indication that the error occurred before the connect() call. This is most likely due to a problem initializing the socket. ...

Today I was curious about whether a certain server was sending me keep-alives.

The fact is that Wireshark is capable of the feat. It has access to the low level data packets and can tell you whether one of those looks like a Keep-Alive sequence (SEG.SEQ) or acknowledgement (ACK).

So if you need to know for a specific server, it's easy enough. You need to connect that specific server and look at the packets using Wireshark.

However, in software, it is not actually possible to determine whether Keep-Alives are being sent. This is because the TCP stack just answers to a signal with a ...

Once in a while, I want to create a struct which has a specific size because it has to match a file one to one.

To do that, you can use a simple trick which is to use a union instead of a struct.

union header_t
{
    char unused[total_size];
    struct
    {
        int field1;
        int field2;
        int field3;
        ...
    };
};

Note that the total size of the union may end up being more than total_size. It's up to you to assert that the size does not go over. However, this is an easy way to create a struct which has a hard coded size. However, it will not be ...

Introduction

This is not the first time I try to look into getting a color in a cell when the value of the cell is such and such, not just smaller than 0 and it becomes [RED]... which is a default available in your formula.

The fact is that you need to create styles that you're going to reference either with the STYLE() function or using the Conditional Formatting window.

So...

P.S. This is only available in Calc.

Creating New Styles and Formatting

First select a cell. You probably want to use an empty cell where you can enter a number or some text and then change it's ...