It is highly advisable to go through Command Line Arguments Post before even looking at the code. Please study this for TCS and come back to this post later.

#include <stdio.h>
int main(int argc, char *argv[])
{
int num,binary,decimal=0,rem,base=1;
num=atoi(argv[1]);
binary=num;
while(num>0)
{
rem=num%2;
decimal =rem*base;
num=num/10;
base=base*2;
}
printf("%d",decimal);
return 0;
}