C programming!?

how to use arrays?


i have to come up with a program that adds up two binary strings.


example:


1001


+ 0001


---------


1010


i dont know how to use array for the carry bit. please help.


i dont know what code to put.

C programming!?
The resulting array can be up to 1 character longer. Just make the result at least 1 character larger than the largest of the 2 numbers being added.





for example


11111111


+11111111


----------------


111111110
Reply:The solution works like the grade-school algorithm for adding multiple digit numbers. (considering each digit as a position in the array).


In this case, instead of adding in base-2 you're making up some other base.





For this example suppose you use base-16 for each block (position in the array). actually any power of two will work provided you want to display the result as a binary string as well. (aside if doing this for decimal notiation you would use some power of 10).





Here is how it works.





#define MASK = 0xFF /* 1111 1111 binary */





int* doAdd(size_t resultlen, int[] lhs, size_t lhslen, int[] rhs, size_t rhslen){


  int* ret = (int*)calloc(MAX(lhslen, rhslen) +1, sizeof(int));


  int temp;


  if (lhslen %26lt; rhslen){ swap(lhs,rhs); swap(lhslen,rhslen);}


  for (int i =0; i %26lt; rhslen; ++i){


   temp= lhs[i] + rhs[i];


   ret[i] = temp % MASK;


   ret[i] = temp / MASK;


  }


  return ret;


}








Note if the input is in the form of character data, the conversion from that into a number is pretty straight forward.





int* convert(char* str, size_t len){


  int* ret = (int*)calloc(len/MASK, sizeof(int));


  int magnitude = 0;


  int pos = 0;


  while( pos %26lt; len / MASK){


   ret[ pos/MASK ] += atoi(str[pos])*magnitude;


   magnitude = (++magnitude)%MASK;


   pos++;


  }


  return ret;


}
Reply:Since I don't want to do your homework for you I will explain how arrays work.





Arrays are literally pointers to a segment of memory. You can have arrays point to a type of memory. These can be integers, booleans, characters, etc..





For example if I wanted to create an array that can contain 5 characters I could do it like so:





char arrMyArray[5];





I can then access each element in the array like so





arrMyArray[0] = 'H'


arrMyArray[1] = 'e'


arrMyArray[2] = 'l'


arrMyArray[3] = 'l'


arrMyArray[4] = 'o'





A simple way to think of them is to visualize an array like a number of crates sitting next to each other on the floor in a straight line. Each crate can only hold one item of the defined type. and you can access these elements based on their location (starting with zero)





So as a hint you may want to start with an array that can hold either integers (int) or booleans (bool)





like:


bool bits[8]





Good luck