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 …
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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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); …
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 …
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 …
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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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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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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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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Reference: http://stackoverflow.com/questions/3164505/mysql-insert-record-if-not-exists-in-table/#3164741 Supposing we have a database table named distributor and we wish to insert a record only if there is no existing record with the same name and country code. The table only has a PRIMARY key but no UNIQUE index on (name, country_code) – think “legacy” and “no privileges to modify database” 😛 …
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