In c language how to find the product of two numbers without using arithmetic operators?

Here is the algorithm (dates from Egyptian times) :





http://www.bitwisemag.com/copy/wilf/wilf...





which translates into C like this:





#include %26lt;stdio.h%26gt;





void main() {


int z = 0, x=101 , y=91;





printf("%d * %d = " , x , y);


while(x %26gt;0) {


if(x%26amp;1) { // is x odd?


z += y;


}


y %26lt;%26lt;=1; // multiple y by 2


x %26gt;%26gt;= 1; // divide x by 2


}


printf("%d" , z);


}





This works but it also needs the + operation so we need to add a function for adding. Complete code is therefore:





#include %26lt;stdio.h%26gt;





unsigned int add(unsigned int a, unsigned int b)


{


unsigned int c= 0;


unsigned int r= 0;


unsigned int t;





for (t= ~0; t; t%26gt;%26gt;= 1)


{


r%26lt;%26lt;= 1;


r|= (a^b^c)%26amp;1;


c= ((a|b)%26amp;c|a%26amp;b)%26amp;1;


a%26gt;%26gt;= 1;


b%26gt;%26gt;= 1;


}


for (t= ~0, c= ~t; t; t%26gt;%26gt;= 1)


{


c%26lt;%26lt;= 1;


c|= r%26amp;1;


r%26gt;%26gt;= 1;


}


return c;


}





unsigned int mul(unsigned int a, unsigned int b)


{


unsigned int r=0;


while(a %26gt; 0)


{


if(a%26amp;1) {


r = add(r, b);


}


b%26lt;%26lt;=1;


a%26gt;%26gt;=1;


}


return r;


}





void main()


{


unsigned int x= 101 , y = 91;





printf("%d*%d= %d\n", x , y, mul(x, y));


}





Source :





http://www.gmonline.demon.co.uk/cscene/C...





Just for info, an introduction to bitwise operators :





http://www.codeproject.com/cpp/bitbashin...





Output is simply





101 * 91 = 9191





Change the values of x and y to check other products.

In c language how to find the product of two numbers without using arithmetic operators?
simple use assignment operator, *=





ie if ya need to multiply a and b


use a*=b;
Reply:by watching the two nos.they constitute the product itself.viz 1 %26amp; 2 are two nos then product of two nos 1 %26amp; 2 is 12
Reply:The only way that I know would only work if one of the numbers was a multiple of 2.





The %26lt;%26lt; (shift left) operator effectively multiplies the number by 2 the number of times specified by the argument.





For example x %26lt;%26lt; 4 multiplies x times 2, 4 times (same as * 16).





The %26lt;%26lt;= is also another way of multiplying by a multiple of 2 and assigning the result to the left side of the equation.