Hmmm when you have the time try the release build

This is the inexplicable optimisation I came across

**Without line 90 commented**

**Debug run**
Code:

selcount = 2403193
Program takes 1.201 seconds.
Press any key to continue . . .

**Release run**
Code:

selcount = 2403193
Program takes 0.390 seconds.
Press any key to continue . . .

**With line 90 commented** (modified code below)

**Debug run**
Code:

selcount = 2403193
Program takes 1.822 seconds.
Press any key to continue . . .

**Release run**
Code:

selcount = 2403193
Program takes 0.530 seconds.
Press any key to continue . . .

Code:

// Compiler VC6.0++
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
/*
An xary number is a number which has the base x
Eg Binary numbers, x = 2
xary numbers can have any base and any lenght
*/
typedef int digit_type;
#include <memory.h>
class xary_number
{
private:
bool xary_number_is_zero;
bool xary_number_is_max;
bool xary_number_is_init;
digit_type max_digit_val; //eg for decimal number, max digit val is 9
digit_type * digit; //All digits in the binary number, eg decimal 3457224024
int xary; //The base of the number eg binary, octal, etc for now only boolean
int lengthneeded; //The number of digits in the number, eg 256 digit hexal, 11 digit hexal
public:
xary_number(int x = 2, int l = 256)
{
xary_number_is_init = false;
init_xary_number(x, l);
};
~xary_number()
{
delete [] digit;
};
void init_xary_number(int x = 2, int l = 256)
{
//Initialize number
xary = x;
lengthneeded = l;
max_digit_val = x - 1;//1 for binary
//create the space for our digits
if(xary_number_is_init)
delete [] digit;
digit = new digit_type[lengthneeded];
//Zero the digits
memset(digit, 0x00, lengthneeded*sizeof(digit_type));
//Initialize some miscellaneous states
xary_number_is_zero = true;
xary_number_is_max = false;
xary_number_is_init = true;
}
void goto_next_selection() //follows the pattern 000, 001, 002, 003, 011, 012, 013, 022, 023, 033, 111, 112, 113, 122, 123, 133, 222, 223, 233, 333 for a 4ary number
{
for(int i = 0; i < lengthneeded; i++)
{
//Removed overflow build up
/*
if(digit[i] == max_digit_val)
{
//needed for miscelaneous is 0
digit[i] = 0;
continue;
}
else
*/
if(digit[i] < max_digit_val)
{
digit[i]++;
//all previous digit equal this digit
digit_type temp = digit[i];
//digit_type * ptr_next_digit = &(digit[i-1]);
//for(i--; i >= 0; i--)
{
digit[i] = temp;
//*ptr_next_digit-- = temp;
}
break;
}
}
//Removed overflow check
/*
//Sets the miscellaneous state to zero if the number overflows to zero
set_if_zero();
//Returns the miscellaneous state
return is_zero();
*/
}
bool is_xary_the_same_as(const digit_type test_xary[]) const
{
//Testing from highest digit to lowest
for(int i = lengthneeded - 1; i >= 0; i--)
{
if(digit[i] != test_xary[i])
{
return false;
}
}
return true;
}
};
int main()
{
//Time declarations
clock_t start, finish;
double elapsed_time;
//Input declarations
FILE * stream;
stream = fopen( "input.txt", "r" );
if( stream == NULL )
{
printf("Error opening file");
return 0;
}
//Getting the first number
int N;
fscanf(stream, "%d", &N);
//Getting the test string
char S[129];
fscanf(stream, "%s", &S);
fclose(stream);
start = clock();
//code start here
//Convert S from a string ABC to an integer arr 123
#define MAX_STR_LEN 128
int Sxary[MAX_STR_LEN];//Assign enough storage space for String array counters
for(int i = 0; i < N; i++)
{
//The first character in the string is the highest digit in the integer array
//Sxary use the same amount of counters as the input string lenght
Sxary[N - i - 1] = S[i] - 'A';
}
const char display_chs[] = "ABCDE";
xary_number sel;
int selcount = 0;
sel.init_xary_number(strlen(display_chs), N);
/*
Testing commented line 90
*/
while(true)
{
selcount++;
if(selcount == 2403193)
{
break;
}
//go from AAA to AAB...AAE to ABB
sel.goto_next_selection();
}
printf("selcount = %d", selcount);
//code end here
finish = clock();
elapsed_time = (double)(finish - start) / CLOCKS_PER_SEC;
printf( "\nProgram takes %0.3f seconds.\n", elapsed_time );
system("pause");
return 1;
}