Added task on command line arguments, added gitignore

Author: maribu

01-introduction/01-hello/.gitignore

@@ -0,0 +1,2 @@
+*.o
+hello

01-introduction/02-make/.gitignore

@@ -0,0 +1,2 @@
+*.o
+hello

01-introduction/03-arguments/.gitignore

@@ -0,0 +1,2 @@
+*.o
+knights

01-introduction/03-arguments/Makefile

@@ -0,0 +1,15 @@
+.PHONY: all clean
+
+CC = gcc
+CFLAGS = -Wall -Wextra -pedantic -Werror -std=c99 -g -O0
+
+all: knights
+
+knights: knights.o
+	$(CC) -o $@ $<
+
+knights.o: knights.c
+	$(CC) -c $(CFLAGS) -o $@ $<
+
+clean:
+	rm -f knights.o knights

01-introduction/03-arguments/README.md

@@ -0,0 +1,33 @@
+# Command Line Arguments
+## Motivation
+Often specific details of the behaviour of a program cannot be configured at
+compile time. Instead, methods to configure a program a run time are needed.
+
+Lets for example look at the shell command `cp`, which creates a copy of a file.
+Specifying the name of the file to copy and the name of the copy to create in
+the C source file of the program `cp` would be terrible for its usability.
+Instead, `cp` allows to specify source and destination at runtime by calling it
+with command line arguments, e.g. `cp orignal_file copy_of_original_file`.
+
+In this task you will learn who to use command line arguments in your own C
+programs.
+
+## Task
+- Create the program `knights`
+	- The source should be placed in `knights.c`. Replace its contents with your
+	  solution
+	- A Makefile for this program is already provided
+- If `knights` is called with no arguments, it should print: "We are The Knights
+  Who Say "Ni!". We demand a shrubbery. One that looks nice. And not to
+  expensive."
+- If the application is called with one or more arguments, of which at least one
+  is "shrubbery", it should print: "We are no longer The Knights Who Say "Ni!".
+  We are now The Knights Who Say Ekki-Ekki-Ekki-Ekki-PTANG. Zoom-Boing.
+  Z'nourrwringmm. Bring us another shrubbery. Slightly higher than the first one.
+  Then you now must cut down the mightiest tree in the forest - with a herring!"
+- If the application is called with five or more arguments, of which at least
+  five are "it", it should print: "Arrhhg!". This has priority over the
+  "shrubbery"-case
+- If no of the cases above match, the command should behave as it was called
+  with no arguments
+- The current source code in `knights.c` contains some useful hints

01-introduction/03-arguments/knights.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int
+main(int argc, const char **argv)
+{
+	// argc = Number of arguments provided + 1
+	// argv = Array of the arguments provided as string.
+	// BUT: argv[0] = Name of the program, argv[1] = The first argument,
+	//      argv[2] = The second argument, ...
+	printf("The name of this program is %s\n", argv[0]);
+	printf("This program was called with %i argument(s)\n", argc-1);
+	
+	if (argc >= 2){
+		// At least one argument
+		if (strcmp("secret", argv[1]) == 0){
+			puts("The first argument was \"secret\"");
+		} else {
+			puts("The first argument was NOT \"secret\"");
+		}
+	}
+	
+	return EXIT_SUCCESS;
+}
+

01-introduction/README.md

@@ -5,3 +5,4 @@ If you are a noob with no experience in C programming, you are right here ;-)
 ## Table of Contents
 - [Hello World](01-hello)
 - [GNU Make](02-make)
+- [Command Line Arguments](03-arguments)