#include #include "string.h" void printfLLasFprc3(char* sfmt, long long iVal){ char slVal[20]; int l; snprintf(slVal, sizeof(slVal), "%9lld", iVal ); l=strlen(slVal); memmove( slVal+l-3, slVal+l-4, 4); slVal[l+1]=0; slVal[l-3]='.'; printf(sfmt, slVal); } long long shiftMul1000(long long iVal){ return ((iVal<<10)-(iVal<<5)+(iVal<<3)); } long long shiftMul1000000(long long iVal){ return ((iVal<<20)-(iVal<<15)- (iVal<<14)+(iVal<<9)+(iVal<<6)); } int main() { int aVal[ ] = { 1, 13, 76, 111, 200, 512, 666, 702, 980, 1022, 1500, 2333, 3444, 5558, 7033, 7777, 10000, 10555, 11444, 12888, 13221, 16666, 22000, 21099, 25566, 29800, 35666, 55555, 77777, 88888, 99999, 111111, 222222, 555555 }; const int cASize = sizeof(aVal)/sizeof(int); float fVal = 0.0; long long laVal = 0, iVal = 0, isVal = 0; long long tisVal = 0; long long tll = 789654; iVal = tll*1000; laVal = shiftMul1000(tll); printf("check mul 10^3 %lld " "vs shift 10^3 %lld\n", iVal, laVal); tll = 789654; iVal = tll*1000000; laVal = shiftMul1000000(tll); printf("check mul 10^6 %lld " "vs shift 10^6 %lld\n", iVal, laVal); printf("\nshift div 3 vs float div 3\n"); for(int i=0;i>1; while( (isVal = -(isVal>>1)) ) iVal+=isVal; printfLLasFprc3( "vs >/3 %s \n", iVal); }; printf("\nshift div 5 vs float div 5 \n"); for(int i=0;i>2; while( (isVal = -(isVal>>2)) ) iVal+=isVal; printfLLasFprc3( "vs >/5 %s \n", iVal); }; printf("\nshift div 7 vs float div 7 \n"); for(int i=0;i>3; while( (isVal = (isVal>>3)) ) iVal+=isVal; printfLLasFprc3( "vs >/7 %s \n", iVal); }; printf("\nshift div 9 vs float div 9 \n"); for(int i=0;i>3; while( (isVal = -(isVal>>3) ) ) iVal+=isVal; printfLLasFprc3( "vs >/9 %s \n", iVal); }; printf("\nshift div 11 vs float div 11 \n"); for(int i=0;i>3; while( isVal ){ tisVal = (isVal>>1); tisVal -= (isVal>>3); isVal = -( tisVal ); iVal+=isVal; }; printfLLasFprc3( "vs >/11 %s \n", iVal); }; printf("\nshift div 13 vs float div 13 \n"); for(int i=0;i>4; while( isVal ){ tisVal = (isVal>>3); tisVal += (isVal>>4); isVal = ( tisVal ); iVal+=isVal; }; printfLLasFprc3( "vs >/13 %s \n", iVal); }; return 0; }

Shift vs div for 3, 5, 7 ,9, 11, 13