Question

I am writing a program, for homework, that will add 2 8-bit binary numbers. I am to use arrays for storage for the read binary numbers. In the function that would actually do the “addition”, it will not execute the for loop. When I step through, it shows the initialization of the variable n for the loop, then it goes straight to the end of loop and exits. Here is my code:

for ( int n = 7; n < 0 ; n-- )
{
    if ( carry == 0 )
    {
        if ( bin1[n] == 0 )
        {
            if ( bin2[n] == 0 )
            {
                sum[n] = 0;
                carry = 0;
            }
            else
            {
                sum[n] = 1;
                carry = 0;
            }
        }
        else
        {
            if ( bin2[n] == 0 )
            {
                sum[n] = 1;
                carry = 0;
            }
            else
            {
                sum[n] = 0;
                carry = 1;
            }
        }
    }
    else
    {
        if ( bin1[n] == 0 )
        {
            if ( bin2[n] == 0 )
            {
                sum[n] = 1;
                carry = 0;
            }
            else
            {
                sum[n] = 0;
                carry = 1;
            }
        }
        else
        {
            if ( bin2[n] == 0 )
            {
                sum[n] = 0;
                carry = 1;
            }
            else
            {
                sum[n] = 1;
                carry = 1;
            }
        }
    }
}

}

I know this may not be the most efficient way to write this so please avoid those answers.

Answer 1

Your condition is false from the start, so the loop exits immediately:

for ( int n = 7; n < 0 ; n-- )

You probably meant:

for ( int n = 7; n >= 0 ; n-- )