Initial commit

assignment/mainpage.h

@@ -0,0 +1,76 @@
+/** @file mainpage.h
+* @brief Description of Pyramid of Numbers.
+*/
+/** @mainpage Pyramid of Numbers
+*
+* @author Peter Bauer
+*
+* @section intro Introduction
+* This weeks assignment deals with an old fashioned primary school problem.
+* Most of you will know the "Turmrechnen" as a pain of your former school
+* days. How it works is shown in the following example
+<pre>
+Pyramid of Numbers
+
+Please enter a number: 3453454359654646756757434
+3453454359654646756757434 * 2 = 6906908719309293513514868
+6906908719309293513514868 * 3 = 20720726157927880540544604
+20720726157927880540544604 * 4 = 82882904631711522162178416
+82882904631711522162178416 * 5 = 414414523158557610810892080
+414414523158557610810892080 * 6 = 2486487138951345664865352480
+2486487138951345664865352480 * 7 = 17405409972659419654057467360
+17405409972659419654057467360 * 8 = 139243279781275357232459738880
+139243279781275357232459738880 * 9 = 1253189518031478215092137649920
+1253189518031478215092137649920 / 2 = 626594759015739107546068824960
+626594759015739107546068824960 / 3 = 208864919671913035848689608320
+208864919671913035848689608320 / 4 = 52216229917978258962172402080
+52216229917978258962172402080 / 5 = 10443245983595651792434480416
+10443245983595651792434480416 / 6 = 1740540997265941965405746736
+1740540997265941965405746736 / 7 = 248648713895134566486535248
+248648713895134566486535248 / 8 = 31081089236891820810816906
+31081089236891820810816906 / 9 = 3453454359654646756757434
+
+</pre>
+* To see more
+* about it's internal structure browse through this documentation.
+* A good starting point is, of course, the function main() and, furthermore, the
+* struct BigInt.
+*
+* When browsing through this documentation you might stumble over the keyword
+* const in the argument list of several functions. This shows you that the argument
+* must not be altered by the function, i.e., you may be sure that, even if a pointer
+* is passed to the function the content of the argument is not changed in the
+* function.
+*
+* @section reading Reading a big number
+* We have to read in the number via a string. Check, whether the entered number
+* does exceed the maximum length of MAX_DIGITS. In this case print an error
+* message and leave the program with error code -1.
+*
+* @section convert Converting to a BigInt
+* The string has than to be converted into a BigInt. Implement a function
+* strtobig_int() as specified. The conversion of one single character c
+* containing a digit to an int can be done via c - '0'. Also think of the
+* correct way to fill the array. Is for the number 123456 the array element
+* a[0] == 1 or is a[0] == 6? Finally do not forget to set BigInt.digits to
+* the right value. After calling
+* strtobig_int() check whether the function was able to convert the entire
+* string. If not an invalid character occured in your string and the program
+* should give an error message and should return with error code -2.
+*
+* @section print Printing a BigInt
+* Should be straight forward.
+*
+* @section calc Multiply and Divide BigInts
+* Do a few multiplications and division by hand (yes as you learned this in
+* primary school :-)). Write down the tiny steps and transform these then into
+* C source code. Keep stuck to the interface multiply() and divide() as given
+* in this documentation. An Engish word you might need for naming a variable:
+* "Uebertrag": carry
+*
+* @section copy Copying a BigInt
+* Take care that simply assigning a BigInt from one variable to another will
+* fail, because the array BigInt.the_int won't be copied but only its pointer.
+* Therefore, you have to write a function copy_big_int(), which copies the
+* array element by element.
+*/