C++: I can't properly get the processing time for this program. Please help. clock_t?

[Lengphrodisiac Balberan]

This is a code which sorts arrays.

I use clock_t to determine the processing time for my code. However, it always stacks with the time taken from before. It looks like it's just adding the results.

int main(int argc, char *argv[])
{unsigned long n;//size of array -- long for big numbers of n
int choice, choice2, sort;//numbers corresponding to the choices(switch)
clock_t Begin, End;
float elapTicks, elapMilli;
wrongchoice://goto function -- bringing back to this point after entering wrong choice
cout<<"===============================…
cout<<"\t\t\tChoose the order of the output:\n\t\t\t\t[1] Random-Descending\n\t\t\t\t[2] Ascending-Descending\n\t\t\t\t[3] Descending-Ascending\n\t\t\t\t[4] Random-Ascending\n\t\t\tChoice: ";
cin>>choice;
cout<<"\t\t\tIndicate size of array: ";
cin>>n;
long int array[n];//first and original array to be used all through the program
long int arrayb[n];//second/temporary array used to preserve/copy original values of first array
for (int i=0; i<n; i++)
{array[i]=rand()%99999;
arrayb[i]=array[i];//copy value of the first array into the second array
}
double temptime=0;
clock_t realend, realend2, realend3, realend4, realend5, realend6;
sorting:
cout<<"\n\t\t\t\t[1] Bubble Sort\n\t\t\t\t[2] Selection Sort\n\t\t\t\t[3] Insertion Sort\n\t\t\t\t[4] Quick Sort\n\t\t\t\t[5] Shell Sort\n\t\t\t\t[6] Merge Sort\n";
cout<<"\t\t\tChoose what sorting algorithm to use: ";
cin>>sort;
goto copyarray;//goto function to copy array elements(located at line 747)
sorting2://goto function -- used to resume back to this point after copying array elements
srand(time(NULL));
switch(choice)//first switch -- indicates the desired order of the output
{
case 1://Random-Descending
{cout<<"==============================…
cout<<"\t\t\tUnsorted Array: "<<endl;
for(int i=0; i<n; i++)
cout<<array[i]<<"\t";
cout<<"\n\n\t\t\tSorted Array:\n";
switch(sort)//second swtich -- indicates what sorting algorithm to use
{
case 1:
{//Bubble Sort Descending
clock_t Begin1, End1;
realend=clock();
Begin1=clock();//indicates start of timer/clock counter(every start of cases for sorting)
BubbleSort2(array, n);//calling of function
End1=clock();//indicates end of timer/clock
float time1;
time1= (End1-Begin1/1000.00f);//used to convert value(taken from the clock code) to milliseconds(from seconds)
cout<<"Bubble Sort:"<<endl;
for (int i=0; i<n; i++)
cout<<array[i]<<"\t";
cout<<"\n\nTotal operational count is: "<<opcount<<endl;
cout<<"\nAlgorithm Runtime is: "<<time1<<" milliseconds.";
cout<<endl<<endl;
goto choose;//goto function to indicate what to do after sorting
break;}
case 2:
{//Selection Sort Descending
clock_t Begin2, End2;
realend2=clock();
Begin2=clock();
double temptime2=Begin2;
SelectionSort2(array, n);//calling of function
End2=clock();
float time2;
time2 = (End2-Begin2/1000.00f);
cout<<"Selection Sort:"<<endl;
for (int i=0; i<n; i++)
cout<<array[i]<<"\t";
cout<<"\n\nTotal operational count is: "<<opcount<<endl;
cout<<"\nAlgorithm Runtime is: "<<time2<<" milliseconds.";
cout<<endl<<endl;
goto choose;//goto function to indicate what to do after sorting
break;}

That is some part of my code. I couldn't put it all here since it's too long. The time adds up with the time that is first taken when I choose another option from the switch code, even though I declared a new variable for clock_t. Please help T_T I really don't know what's wrong with the code.

Here's the entire code:

http://www.daniweb.com/software-development/cpp/threads/416130/1775548#post1775548



Feel free to paste it in any c++ debugger so you would understand the code better.

I hope someone can help me.

[cire]

It would be easier to understand if you posted stuff that:

was indented.

used whitespace.

compiled.

Wasn't sprinkled with goto.

Was whittled down to a (compilable) example of reasonable size that demonstrated the problem.

[coder777]

Look at this http://www.cplusplus.com/reference/clibrary/ctime/clock/ to use clock() properly

EDIT: This (End1-Begin1/1000.00f) doesn't convert seconds to miliseconds. Even if it did you won't get more accuracy from calculating seconds to milliseconds