add without using +,++ or -,--

otadd0.c

/* otadd0.c : add without using +,++ or -,-- */
/* clean:
int add(int a, int b)
{
        int r,n,c;
        for(r=c=0,n=1;n;n<<=1) {
                c = (a & b) ^ (c & (a ^ b));
                c <<= 1;
                r |= (a ^ b ^ c) & n;
        }
        return r;
}
*/
/* compressed */
int add(int a,int b){
int r,n,c;for(r=c=0,n=1;n;n<<=1){c=(a&b)^(c&(a^b));c<<=1;r|=(a^b^c)&n;}return r;
}
/** test code **/
/* to use:
 * ./otadd0 33 66
 * ./otadd0 -5 -3
 * ...
 */
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
        printf("%d\n",add(strtol(argv[1],0,0),strtol(argv[2],0,0)));
        return 0;
}