Two ways to convert decimal numbers to binary strings

I'll show you two ways to convert decimal to binary.

First, the most basic way is apply the following pseudo-code:

int x
char[80] arr
do{
   reminder = x%2;
   arr[i] = reminder
}while (x/2 > 0);
reverse arr;

And the other is more advanced (and more simple), it use bitwise operations instead:

int x
while (x > 0){
        arr[i] = ((x & 1) ? '1' : '0');
        x >>=1;
}
reverse arr

and here's a C code for the last one:

 
//I am not the author of this function, I copied from the link below
void dec2binary(long i){
    
    char* str = malloc(sizeof(long)*8*sizeof(char));
    
    char* p = str;
    while (i > 0){
        *p++ = ((i & 1) ? '1' : '0');
        i >>=1;
    }

    while( p-- != str ) /* print out the result backwards */
        printf("%c",*p);

    free(str);
}

please see:
http://www.daniweb.com/code/snippet216349.html

Shift operators in Java

Here's a very simple lesson that illustrate the shift operators in java

http://www.sap-img.com/java/java-bitwise-shift-operators.htm

Summary:

We have three shift operators in java >>, >>> and <<

1- >>
definition:
right shift with the outermost (hi bit) value
example:
9>> 2
9 in binary is 0000000000001001
so, we need to shift right 2 bites adding instead 2 bits of the hi bit
so, result will be 0000000000000010

2- >>>
It is the same as the above, but adds 0 at the left most (not the hi bit)
so, suppose we have
-1 >> 2
-1 in binary is 1111111111111111 (the 2's complement of 1)
so, the result will be -1 also. but if we applied >>> instead, we will always add 0's to the left of the bit pattern.

3- <<
left right is the oposite to the left shift (<<), that add the hi bit from the right.
ex:
9 << 1
9 in binary is 0000000000001001
result will be 0000000000010010 (in decimal is 18 )

(please let me know if there's any errors because I wrote that conclusion in hurry ;) )