ns2 installation, problems and solutions on fedora

One of the most easiest way to install ns2 is to download ns-allinone package. So download ns-allinone-2.34.tar.gz. now follow these steps.
1. go to directory where you saved tar.gz file and execute following command
tar -xzf ns-allinone-2.34.tar.gz
2. cd ns-allinone-2.34/
3. now install the package using (switct to root or use sudo)
./install
4. first problem you encounter is "g++ command not found" otherwise skip this step
soln- yum install gcc-g++
now try 3rd step again
5. you might encounter problem of "/home/user.../generic/tk.h:557: error expected declaration specifiers or '...' before 'Window' and similar other errors while installing tk (otherwise skip this step)
soln- yum install libX11-devel
now try 3rd step
6. if you get "can't find X includeds otcl-1.13 configuration failed! Exiting.."
soln- yum install libXt-devel or yum groupinstall "X Software Development" later one is better.
now try 3rd step and it will run successfully

using binary number in C or C++

Many C learner face the problem of initializing a variable with binary value or assign a integer variable with binary values. Don't worry its very easy as described in C you can use 0x for hex, 0 for octal similarly 0b defines binary. for example if you want to assign binary 1101 (i.e 13) to variable. then use this
int var = 0b1101;

undefined reference to static variable in c++

Suppose i have a code which need to reference static variable

so we have following code in trial.h

class Trial

{

static int v;

void setCode();

}

in trail.cc

#include "trial.h"

void Trial::setCode()

{

v=1;

}

This above code will give undefined reference to Trial::v error. To remove this error either remove static word from v in .h file or if it is necessary to have static word. then do as following.

in trial.cc

#include "trial.h"

int Trial::v;

void Trial::setCode()

{

v=1;

}

now your error is gone . happy coding