reverse_digits_of_number_optimized.c

/*

    reverse_digits_of_number_optimized.c

    by Walter Whitman

    https://web.facebook.com/waltersmind


    Here is the optimized code for integer reversal,

    optimized to the max in a short amount of time.

*/

#include <stdio.h>


// return NewValue, which is reversed digits of ValueToReverse
unsigned long long int reverse_digits_of_number_optimized( unsigned long long int ValueToReverse, unsigned long long int *NewValue )
{
    while(ValueToReverse > 0)
    {
        *NewValue = *NewValue * 10 + (ValueToReverse % 10);
        ValueToReverse /= 10;
    }

    return( *NewValue );

} // reverse_digits_of_number_optimized()


int main(void)
{
    unsigned long long int ValueToReverse = 123456789;
    unsigned long long int NewValue = 0;


    printf("\n Enter ValueToReverse = ");
    scanf("%llu",&ValueToReverse);


    printf("\n ValueToReverse: %llu \n", ValueToReverse );

    //NewValue = reverse_digits_of_number_optimized( ValueToReverse, &NewValue );
    reverse_digits_of_number_optimized( ValueToReverse, &NewValue );

    printf("\n NewValue:       %llu \n", NewValue );


    return 0;

} // main()