Mark: 13 revision(s)

2008-11-03T05:20:31Z

13 revision(s)

New page

First off it wouldn't compile.
/cygdrive/c/Users/sdal039/AppData/Local/Temp/ccztcwNj.o:lab-8.c:(.text+0x30b): undefined reference to `_strcimp'
collect2: ld returned 1 exit status

Thanks to hpan027 for putting up solution, which was to search for 'strcimp' in parsetree.c and replace with 'stricmp'.

'''Task 1'''

k.

'''Task 2'''
ParseTree* expr = mkNode('-', mkNode('-', mkNode('a', 0), mkNode('b', 0), 0), 0);
prefix_tree( expr );

Unfortunately the tree_to_graph function still only seems to produce .dot files, so Graphviz had to be used again to convert the .dot to a .jpeg.
Sweet, just found the fix for this. Much easier now. Awesome points for those who figured that out.

[http://img81.imageshack.us/my.php?image=graph1og9.jpg Graph 1]

'''Task 3'''
mkNode('?', mkNode('>', mkNode('+', mkNode('a', 0), mkNode('b', 0), 0), mkNode('c', 0)),
mkNode('*', mkNode('z', 0), mkNode('+', mkNode('y', 0), mkNode('b', 0), 0), 0),
mkNode('?', mkNode('=', mkNode('a', 0), mkNode('2', 0) , 0 ),
mkNode('-', mkNode('x', 0), mkNode('y', 0) , 0 ),
mkNode('-', mkNode('y', 0), mkNode('x', 0) , 0 ) , 0 ));
prefix_tree( expr2 );

Many parentheses later, this produced
?(>(+(a b) c) *(z +(y b)) ?(=(a 2) -(x y) -(y x)))

'''Task 4'''

[http://img81.imageshack.us/my.php?image=graph2is1.jpg Graph 2]

There were not any discrepancies between what I had down on paper and what the graph produced. This implies that either there wasn't supposed to be any differences, or I didn't make my nodes correctly.

'''Task 5'''

Because the '?' node has three children, there is no ambiguity as to which expression belongs where. The ':' is used in C to differentiate between e1 and e1, whereas this is not needed for the parse tree as e1 and e2 are physically separated.
For example, with the ternary expression (a == 0) ? b = 5 : b = 4;
The tokenizer needs the ':' to split up 'b = 5' and 'b = 4' into different tokens, but once this has been done, the parse tree structure will ensure they remain separated.

'''Task 6'''

Looks hard...

int eval( ParseTree* t ) {
return t->name;
}

This code works for individual numbers at least. :P

SE250:lab-8:sdal039 - Revision history

Mark: 13 revision(s)