Blog @ intZone

2018-05-222018-11-29

Swift func to show alert dialog in AppDelegate or ViewController

Was trying to show an alert dialog in a project’s AppDelegate.swift and ViewController.swift and decided to move it to a function in a separate utility class. Main issue was how to make it work as the class was a plain Swift class – self.present() could be used inside ViewController, self.window?.rootViewController?.present() could be used inside AppDelegate, …

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2018-03-122018-07-13

Making an App isn’t Easy

Imagine going into a restaurant. You see a nice decor, with tables laid out in an orderly fashion, pretty tablecloth, walls sprinkled with beautiful artwork, ambient lighting, etc. You pick up the nicely done up menu with attractive photos, juicy titles, succulent descriptions and a myriad of options for each dish. Hidden from your view …

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2017-10-162018-11-29

Print out type of literal or variable in C

References: Is there a way to print out the type of a variable/pointer in C? Why are C character literals ints instead of chars? Was trying to find out the type of char/string literals in C. Found a hackish way of doing it. Source code: test.c #include <stdio.h> int main() { char *s = “ABC”; …

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2017-09-05

Pointer initialization in C

Just a simple program to see the effects of pointer initialization in C. Program: #include void main() { int *p; printf(“&p = %p, p = %p\n”, &p, p); /* // This will cause segmentation fault *p = 5; printf(“*p = %d\n”, *p); */ int *q = 0; printf(“&q = %p, q = %p\n”, &q, q); …

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2017-08-142018-11-29

Simple test program on pointers in C

This post only documents a simple program to show the effects of * and & in C and does not attempt to explain what pointers are. For a quick read, check out The 5-Minute Guide to C Pointers. Program: #include <stdio.h> int main() { // lval (left-hand side value – write) = rval (right-hand side …

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2017-08-012018-11-29

List tables with table size in MySQL

The following query will list the top 5 tables by table size in MySQL. SELECT TABLE_SCHEMA, TABLE_NAME, CEIL((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024) AS table_size_in_MiB, TABLE_ROWS AS estimated_row_count, AVG_ROW_LENGTH FROM information_schema.TABLES WHERE TABLE_SCHEMA NOT IN (‘information_schema’, ‘innodb’, ‘mysql’, ‘performance_schema’, ‘phpmyadmin’, ‘sys’, ‘tmp’) ORDER BY table_size_in_MiB DESC LIMIT 5; Note that TABLE_ROWS is only accurate …

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2017-07-172018-11-29

Print QR code to network-enabled thermal receipt printer using Java

For more information on the ESC/POS command set which receipt printers use for printing, see What is ESC/POS and How Do I Use It by Michael Billington, also the author of the excellent escpos-php PHP library for receipt printers. Thanks to this StackOverflow post as well: printing QR codes through an ESC/POS thermal printer? 🙂 …

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2017-06-302018-11-29

Print Chinese text to network-enabled thermal receipt printer using Java

For more information on the ESC/POS command set which receipt printers use for printing, see What is ESC/POS and How Do I Use It by Michael Billington, also the author of the excellent escpos-php PHP library for receipt printers. Steps to run: Save the code below as NetworkReceiptPrinter.java – change printer IP accordingly. Run javac …

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2017-05-30

Use absolute paths for filenames when running PHP scripts in cron jobs

Writing this down after spending a few hours figuring what went wrong…was adding a cron job to the root crontab for a PHP script which ran fine by itself but not so when executed by the cron job. Entry in root crontab (sudo crontab -e): # Run PHP script every 3 hours between 9am – …

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2017-05-23

Adding a secondary router with Wi-Fi and staying on the same subnet

Scenario: Broadband modem and primary router located on 1st floor. PC and network printer on 1st floor connected to primary router. Ethernet cable from LAN port 4 of primary router laid from 1st floor to 2nd floor and connected to a Mac on the 2nd floor. Additional cable needed on 2nd floor for a new …

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