Priyadeep's Blog

Link list

priyadeep — Mon, 26 Jul 2010 16:03:17 +0000

A link list have
start pointer and
number of nodes – each have data stored and pointer to next node.

must have pointers
* Start pointer -> to tell where the list started
* next node pointer-> to tell where is next node placed

optional pointers ( to increase the efficiency of link list)
* last pointer -> will point to the last node of link list
* previous pointer -> will point to previous node .

#include using namespace std;
struct Node{ int data_; Node* next_; Node* prev_; }; class LList{ Node* start_; Node* last_; public: LList(); void addFront(int v); void removeFront(); void addBack(int v); void removeBack(); void print(); ~LList(); }; LList::LList(){ start_=last_=NULL; } void LList::removeFront(){ if(start_){ Node* rm=start_; if(start_==last_){ //only have one node in list last_=NULL; } start_=start_->next_; delete rm; } } void LList::addFront(int v){ Node* newnode=new Node; newnode->data_=v; if(!start_){ //link node to empty list start_=newnode; last_=newnode; newnode->next_=NULL; } else{ newnode->next_=start_; start_=newnode; } } void LList::print(){ Node* curr=start_; for(Node* curr=start_;curr;curr=curr->next_){ cout delete curr; curr=nextnode; } } void LList::addBack(int v){ Node* nn=new Node; nn->data_=v; nn->next_=NULL; if(last_){ //not empty list last_->next_=nn; } else{ start_=nn; } last_=nn; } void LList::removeBack(){ if(start_){ if(start_!=last_){ Node* secondlast=start_; while(seconlast->next_!=last){ secondlast=secondlast->next_; } secondlast->next_=NULL; delete last_; last_=secondlast; } else{ delete last_; start_=NULL; last_=NULL; } } } void print(int& x){ cout << x << endl; } void increase(int& x){ x=x+1; }

Bitwise Operators (shifts)

priyadeep — Fri, 18 Jun 2010 00:51:08 +0000

left shift

Lets we have A=0000 0100 which is actually ’4′
Now the magic time
left shift a by 1
A<<1
= 0000 1000 which is equal to '8'
so left shift is multiply by 2

another example :- X= 0001 0000 = ’16′
X<<1 = 0010 0000 ='32'

Right shift
A<<1 = 0000 0100 ='4'
X<<1= 0001 0000 ='16'

This mean right shift is divide by ’2′

Next time you wanna divide or multiply bits do shifts

Command line programming

priyadeep — Fri, 18 Jun 2010 00:24:33 +0000

Actual main =>
int main(int argc, char * argv[]){
int i;
for(i=0;i printf("%d- %s\n", i, argv[i]);
}
return 0;
}

Where
argc -> number of arguments passed and
argv[] -> array of arguments

function to find the average of ‘n’ numbers

double average(int num, …){
double sum = 0;
int i;
va_list args; /*To hold the arguments*/
va_start(args, num); /* to give the list of argument that ends with ‘num’ */
for(i=0;i sum += va_arg(args, double);
}
va_end(args);
return sum/num;
}

But the arguments passed are not allowed zero because it has find the last one to stop looking further
va_list is predefined structure

Void pointers

priyadeep — Mon, 07 Jun 2010 16:25:58 +0000

void *
is a pointer that if we have learnt before or with all other type of pointers would not have that value.
Anyways it is simple as that this is a variable pointing to a memory address and it does not know what is the type of variable whose address it is pointing to ….
also called generic pointer
It is good for the situations where we need to store different kinds of addresses .

#include
int main(void) { char ans; void *p; printf("Enter 'i' for int or 'c' for char ? "); scanf("%c", &ans); printf ("Enter the value : "); if (ans == 'i') { int a; scanf("%d",&a); *(int *)p = a; } else { char c; c=getchar(); scanf("%c",&c); *(char *)p=c; }
printf("value is:"); if(ans=='i') { int a=*(int *)p; printf("int is %d" , a); } else { char c=*(char *)p; printf("char is %c" ,c); } return 0; }

SVN is it secure

priyadeep — Mon, 07 Jun 2010 14:30:39 +0000

SVN, a new branch in my life. It is so convenient and let you think about your code , no need to care about uploading and downloading. But is it really that good … a folder siting in middle of your data that has special access to a server and that server has access to your computer …. never mind to give passwords or any thing for authentication or security once you have repository there .
I would really appreciate if any one will try to convince my for it security features..

Instructions for coding by Fardad

priyadeep — Wed, 26 May 2010 02:25:30 +0000

* Add ground rule for coding
- indentation for three,two or four spaces
- starting bracket in end of function name line or in the start of next line.
* Single entry point
* Single exit point
- Only one return statement in a function
* No break, continue or goto

—————–
Compiler passes

While compilation c/c++ compiler make at least three passes to program

- First pass is PRE-PROCESSOR
Embed the full code in place of # directives (#include,#define)
- Second pass is compiler
Translate source code to machine language called object file.
- Third pass is linker
Combines object code and extract code from standard libraries, all external references make executable program .

COOL things we discuss today(19 th may)

priyadeep — Wed, 19 May 2010 23:29:04 +0000

? : Ternary operator

c = a > b ? 100 : 200 ;

* Faster then IF statement
* Data types for both the values (100 and 200) should be same.

———

a=10;
b=20;
printf(“%d %d \n”, b, b+1);

output is -> 21 21

because compiler use stack so first b will go in then b+1 will go into the stack
As stack is LIFO
so it will take b+1 out first so now b = 21;
then b
so the printout is
21 21
But it depends purely on the compiler if it uses queue then the answer will be
20 21

———-

printf returns number of characters successfully printed.
-1 if it fails to run
———-

Preprocessor directive
#include
# -> pre-processor directive (tells the compiler to do something before compiling .
include -> brings in contents of file given next to it

define ->search and replace
#define sum a+b
will replace the word sum with a+b before compiling

* Define is also used to create macros (macros -> smart search and replace)
#define SUM(x,y) ((x)+(y))
* Compiler can be directed to compile or not to compile any part of code

#define one 1
#define two 2
#define comp one

int main()
{
…
…
ifdef comp== one
…
…
#endif
ifdef comp== two
…
…
#endif
#else
…
…
#endif
…
}

Feel free to correct me if you find anything wrong and if you want to add on what we did in class or any thing regarding oop344

Tools for OOP344

priyadeep — Wed, 19 May 2010 22:47:02 +0000

Things we need to get OOP344 going
* WIKI account -> own page , Team page , entry in student list, entry in team list .
* IRS(CHATZILLA)
* A Blog
* SVN

I would like if any one update if we need any thing else….

start up

priyadeep — Sat, 15 May 2010 22:22:00 +0000

Hi this blog is for school course oop344. I am expecting to discuss about c/c++ project .