pstef’s gists

pstef / gist:4726614

Last active December 12, 2015 06:08

	memcpy(d, s, n)[n - 1] = 0;
	memmove(d, s, n)[n - 1] = 0;

pstef / gist:4750224

Created February 10, 2013 17:02

<zid`> There's a really cryptic gcc command you can invoke to tell you all the #defines that are in a blank C file

gcc -dM -E - < /dev/null

pstef / gist:4996382

Created February 20, 2013 15:32

From ##C: number of decimal digits an unsigned integer type can have at most

	#include <stdio.h>
	#include <limits.h>

	/* number of decimal digits an unsigned integer type can have at most,
	* not including the terminating 0 byte of strings.
	* One needs log_10(2) digits per bit, 28/93 is slightly above this value.
	* If bits * 28 is not divisible by 93, the result is truncated and one byte
	* short, hence add 1.
	*
	* E.g. one needs 32 * l(2)/l(10) ~ 9.6323 ~ 10 bytes for 32 bit unsigned int.

pstef / gist:5072515

Last active December 14, 2015 10:29

GNU indent: what exactly -gnu is

	-gnu - Use GNU coding style. This is the default.
	----------------------------------------------------------------------------------------------
	-nbad - Do not force blank lines after declarations.
	-bap - Force blank lines after procedure bodies.
	-nbc - Do not force newlines after commas in declarations.
	-bbo - Prefer to break long lines before boolean operators.
	-bl - Put braces on line after if, etc.
	-bli2 - Indent braces 2 spaces.
	-bls - Put braces on the line after struct declaration lines.
	-ncdb - Do not put comment delimiters on blank lines.

pstef / gist:5161793

Last active December 14, 2015 22:58

Books to read and re-read.

	Kernighan and Ritchie: The C Programming Language

	Stephen Prata: C Primer Plus
	Brian Hook: Write portable code
	Andrew Koenig: C traps and pitfalls
	Peter v d Linden: Expert C programming - Deep secrets
	C Unleashed

	Jon Bentley: Programming Pearls
	Robert Sedgewick: Algorithms in C

pstef / gist:5189951

Created March 18, 2013 19:13

Toggle Valgrind data collection on entry/exit of function

valgrind --tool=callgrind --toggle-collect=function ./program

pstef / enum.c

Created March 21, 2013 13:34

Why I didn't like enum types in C until I learned about clang -Weverything -fsanitize=enum

	#include <string.h>
	#include <stdio.h>

	enum car { honda };

	enum number { ZERO, ONE };

	enum number function_returning_number(char const *keyword) {
	if (!strcmp(keyword, "zero"))
	return ZERO;

pstef / last-components.sql

Last active August 29, 2015 13:56

<lluad> Is there a tidier way to get the last two components of a hostname than (regexp_matches(foo, '\.([^.]+\.[^.]+)$'))[1] ? It works, but kinda offends even me. It's only going to be used on hostnames, so I don't really care what it does to non-hostname input.

	SELECT array_to_string(a[array_upper(a, 1)-1:array_upper(a, 1)], '.')
	FROM string_to_array('gist.github.com', '.') a

pstef / linspector

Last active March 13, 2016 18:27


	psql -d 'linspector' <<EOF
	DROP TABLE IF EXISTS symbols, "files";
	CREATE TABLE symbols (
	filename text NOT NULL,
	flag "char" NOT NULL,
	symbol text NOT NULL,
	PRIMARY KEY (filename, flag, symbol)
	);
	COPY symbols (filename, flag, symbol) FROM stdin;

pstef / Postgres-json-output.txt

Last active October 21, 2018 07:58

Showing of Postgres's features

	WITH
	manufacturers (name, headquarters) AS (VALUES
	('BMW', 'Munich'), ('Toyota', 'Toyota'), ('Fiat', 'Turin')
	),
	models (manufacturer, name, year) AS (VALUES
	('BMW', 'm4', 2000), ('BMW', 'm5', 2000),
	('Toyota', 'corolla', 2000), ('Toyota', 'yaris', 2000),
	('Fiat', 'panda', 2000), ('Fiat', 'uno', 2000)
	),
	products (manufacturer, model, color, quantity, pretax) AS (VALUES