if statement doesn't work

[fizcalpolicy]

I compiled and ran the following program without success. I finally gave up and tried running the one that came with the textbook (Accelerated C++) and still no luck. Is the program wrong or am I doing something incorrectly?? I added system ("pause") to "freeze" the console (windows)


#include <algorithm>
#include <iomanip>
#include <ios>
#include <iostream>
#include <string>
#include <vector>

using std::cin; using std::sort;
using std::cout; using std::streamsize;
using std::endl; using std::string;
using std::setprecision; using std::vector;

int main()
{
// ask for and read the student's name
cout << "Please enter your first name: ";
string name;
cin >> name;
cout << "Hello, " << name << "!" << endl;

// ask for and read the midterm and final grades
cout << "Please enter your midterm and final exam grades: ";
double midterm, final;
cin >> midterm >> final;

// ask for and read the homework grades
cout << "Enter all your homework grades, "
"followed by end-of-file: ";

vector<double> homework;
double x;
// invariant: `homework' contains all the homework grades read so far
while (cin >> x)
homework.push_back(x);

// check that the student entered some homework grades
typedef vector<double>::size_type vec_sz;
vec_sz size = homework.size();
if (size == 0) {
cout << endl << "You must enter your grades. "
"Please try again." << endl;
return 1;
}

// sort the grades
sort(homework.begin(), homework.end());

// compute the median homework grade
vec_sz mid = size/2;
double median;
median = size % 2 == 0 ? (homework[mid] + homework[mid-1]) / 2
: homework[mid];

// compute and write the final grade
streamsize prec = cout.precision();
cout << "Your final grade is " << setprecision(3)
<< 0.2 * midterm + 0.4 * final + 0.4 * median
<< setprecision(prec) << endl;
system("pause");
return 0;
}

[filipe]

How is the program behaving? Does it compile? Do you get an error message?

Please use [ code ] [ /code ] tags (without the spaces) next time.

[hamsterman]

What's the error message? The code works fine for me.

[m4ster r0shi]

The program runs fine... What's your problem? (note that end-of-file means control+Z)

[Athar]

ran the following program without success.

What does that mean?

no luck

No luck with what?

[fizcalpolicy]

The if statement doesn't run, when size==0.......console dissapears when data entered is incorrect or empty.

please help

[Galik]

How are you expecting the user to indicate that he has finished typing in all his grades?

[fizcalpolicy]

end-of-file

[Galik]

You are doing nothing to pause the console if the list is empty.

Try something like this:

	if(size == 0)
	{
		cout << endl << "You must enter your grades. "
			"Please try again." << endl;
		cin.clear(); // clear end of file flag
		cin.ignore(); // wait for key press
		return 1;
	}

[fizcalpolicy]

I tried this with and without system("pause") I still do not get the string lateral to apear when size==0.....Could it be the compiler itself (Dev-C++)??

Where you able to run the program while size==0 with the following message on the console?:

you must enter your grades.
Please try again

[Galik]

Yes, it works fine for me. Prints the message in full.

You must enter your grades. Please try again.

[fizcalpolicy]

Do you think it could be my compiler?

[Galik]

You could try it on a different compiler or a different version of the same compiler.

[fizcalpolicy]

Could you recommend an alternative? I am currently using Dev C++

[m4ster r0shi]

Try CodeBlocks

[fizcalpolicy]

Thanks

[guestgulkan]

if (size == 0) {
cout << endl << "You must enter your grades. "
"Please try again." << endl;
return 1;
}

Whether the console dissapears or not depends on your IDE. - some of them keep the console
open during a debugging run after the program terminates, others closes the console.

The OP's closes the console - he can use cin.get(), or even system("pause") - yes, I know, Iknow - to keep the console open.