What's the code you'd use in a simplified division function?

I know for multiplying, a simplified function can use addition.

Ask for two numbers to be multiplied.

mult( x, y);

And then simply

Add x, y times.

But given two numbers, how could you carry out division in a similarly simplified manner? That is without using "/".

div(x,y)


say you wanted to do x / y


for example 9 / 2

int result = 0;
while(x > y){
x = x - y;
++result;
};

int remainder = x;

that would work like:

while 9 > 2

result = 1

x = 7;

while 7 > 2

result = 2

x = 5

while 5 > 2

result = 3;

while 3 > 2

result = 4

x = 1

while 1 > 2 is false, so loop breaks

remainder = 1


so the result is 4 remainder 1

So division just using subtraction? Okay, here you go in C++:

int divide ( int x, int divisor, int & remainder );
int divide ( int x, int divisor, int & remainder )
{
if ( x > divisor )
return 1 + divide ( x - divisor, divisor, remainder );
else
{
remainder = x;
return 0;
}
}

int main(int argc, char* argv[])
{
int remainder;
int result = divide ( 105, 8, remainder );
printf ( "105/8 = %d, remainder = %d\n", result, remainder );

getchar();
return 0;
}

If you are dividing a number by a power of two (i.e. x / 2^k), then by FAR the fastest divide function possible is to do a bit-wise right shift. In c/c++, this would be x>>k.

To divide normal numbers, do it like you did in fourth grade. Have an accumulator and subtract the dividend by the divisor, incrementing the accumulator each time, until the dividend is less than zero.

Example (c/c++):

int divide(int x, int y)
{
int result = 0;

while ( true )
{
x = x - y;
if ( x < 0 ) break; // jump out of the while loop

result++;
}

return result;
}