Programming Forums > Application Development > C++

SonicReducer · Apr 9th, 2007, 8:54 PM

What exactly does this program do? I don't get why the for loops would add one to the number the user types in if the number is less than the maximum number. I got this code from an ebook by the way, and I get compiler errors when I try to compile and run it in DevC++.

(Toggle Plain Text)

#include <iostream>
using namespace std;
const int MAX = 3;
int main ()
{
   int testScore[MAX];
   for (int i = 0; i < MAX; i++)
   {
      cout << "Enter test score #" << i + 1 << ": ";
      cin >> testScore[i];
   }
   for (i = 0; i < MAX; i++)
   {
      cout << "Test score #" << i + 1 << ": "
         << testScore[i] << endl;
   }
   return 0;
}

ReggaetonKing · Apr 9th, 2007, 8:59 PM

the second for loop does not declare your variable i as an integer value.

(Toggle Plain Text)

#include <iostream>
using namespace std;
const int MAX = 3;
int main ()
{
   int testScore[MAX];
   for (int i = 0; i < MAX; i++)
   {
      cout << "Enter test score #" << i + 1 << ": ";
      cin >> testScore[i];
   }
   for (int i = 0; i < MAX; i++)
   {
      cout << "Test score #" << i + 1 << ": "
         << testScore[i] << endl;
   }
   return 0;
}

SonicReducer · Apr 9th, 2007, 9:19 PM

Thanks, I can compile the program now. But my question was really about the code. i equals 0, if it's less than MAX add 1? So if I typed in 22 it would become 23? Wouldn't that mess things up?

Also, when I run the program it closes immeadiately after I've entered the 3 numbers, so any number that it puts out, I can't see. How can I fix this?

DaWei · Apr 9th, 2007, 9:25 PM

(Toggle Plain Text)

      cin >> testScore[i];

Test that statement for success. If the user enters a non-numeric, it'll break your program. Refer to your documentation

The 1 is being added strictly for presentation purposes. Arrays begin with element 0. Adding one to the number results in

(Toggle Plain Text)

1.   score from array 0
2.   score from array 1
3.   score from array 2

rather than:

(Toggle Plain Text)

0.   score from array 0
1.   score from array 1
2.   score from array 2

Don't post, "I got errors," or "It doesn't work." State the errors precisely and indicate the lines on which they occurred, if possible. If you get it running, and "It doesn't work," explain how it fails to meet your expectations.

Have a look at the "How to Post a Question" thread, it's a sticky right at the top of this forum.

SonicReducer · Apr 10th, 2007, 12:07 AM

Quote:

Originally Posted by DaWei

Don't post, "I got errors," or "It doesn't work." State the errors precisely and indicate the lines on which they occurred, if possible. If you get it running, and "It doesn't work," explain how it fails to meet your expectations.

Have a look at the "How to Post a Question" thread, it's a sticky right at the top of this forum.

Sorry about that, but I didn't really care about the code working or not. I just wanted to understand the for loops. I think I've got it now, thanks for yet another good reply.

DaWei · Apr 10th, 2007, 3:36 AM

Look at your code again. The number you enter (testscore [i]) is not getting one added to it. The COUNTER (i) is getting one added to it.

Programs run until they complete, then terminate. If you run your program from the command line, then the window belongs to command.exe. When your program completes, command.exe will put out another prompt in the same window. Your output will still be showing.

If you run your program in its own window (double-clicking its icon, say), then it will terminate and the window will close.

If the IDE (if you have one) provides the window, then IT will stay open, but if it spawns a window specifically for that execution, the window will close.

Note that the key word is "terminate". You may add an input statement to the end of your program so that it doesn't terminate until you provide it input. It'll sit there and wait for that, giving you plenty of time to look. You can use "cin.get ()."

You will need to clear the input before "cin.get ()" in case your user has pounded in some extraneous stuff. You can use cin.sync (), although there is some controversy regarding its standardized applicability to a basic_istream, or you may use cin.ignore (). See your documentation.

Apr 9th, 2007, 8:54 PM	#1
SonicReducer Newbie Join Date: Mar 2007 Posts: 7 Rep Power: 0	For Loops in this Code What exactly does this program do? I don't get why the for loops would add one to the number the user types in if the number is less than the maximum number. I got this code from an ebook by the way, and I get compiler errors when I try to compile and run it in DevC++. (Toggle Plain Text) #include <iostream> using namespace std; const int MAX = 3; int main () { int testScore[MAX]; for (int i = 0; i < MAX; i++) { cout << "Enter test score #" << i + 1 << ": "; cin >> testScore[i]; } for (i = 0; i < MAX; i++) { cout << "Test score #" << i + 1 << ": " << testScore[i] << endl; } return 0; } #include <iostream> using namespace std; const int MAX = 3; int main () { int testScore[MAX]; for (int i = 0; i < MAX; i++) { cout << "Enter test score #" << i + 1 << ": "; cin >> testScore[i]; } for (i = 0; i < MAX; i++) { cout << "Test score #" << i + 1 << ": " << testScore[i] << endl; } return 0; }

Apr 9th, 2007, 8:59 PM	#2
ReggaetonKing Sexy Programmer Join Date: Nov 2005 Location: New Jersey Posts: 891 Rep Power: 3	the second for loop does not declare your variable i as an integer value. (Toggle Plain Text) #include <iostream> using namespace std; const int MAX = 3; int main () { int testScore[MAX]; for (int i = 0; i < MAX; i++) { cout << "Enter test score #" << i + 1 << ": "; cin >> testScore[i]; } for (int i = 0; i < MAX; i++) { cout << "Test score #" << i + 1 << ": " << testScore[i] << endl; } return 0; } #include <iostream> using namespace std; const int MAX = 3; int main () { int testScore[MAX]; for (int i = 0; i < MAX; i++) { cout << "Enter test score #" << i + 1 << ": "; cin >> testScore[i]; } for (int i = 0; i < MAX; i++) { cout << "Test score #" << i + 1 << ": " << testScore[i] << endl; } return 0; } __________________ I would love to change the world, but they won't give me the source code!

Apr 9th, 2007, 9:25 PM	#4
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	(Toggle Plain Text) cin >> testScore[i]; cin >> testScore[i]; Test that statement for success. If the user enters a non-numeric, it'll break your program. Refer to your documentation The 1 is being added strictly for presentation purposes. Arrays begin with element 0. Adding one to the number results in (Toggle Plain Text) 1. score from array 0 2. score from array 1 3. score from array 2 1. score from array 0 2. score from array 1 3. score from array 2 rather than: (Toggle Plain Text) 0. score from array 0 1. score from array 1 2. score from array 2 0. score from array 0 1. score from array 1 2. score from array 2 Don't post, "I got errors," or "It doesn't work." State the errors precisely and indicate the lines on which they occurred, if possible. If you get it running, and "It doesn't work," explain how it fails to meet your expectations. Have a look at the "How to Post a Question" thread, it's a sticky right at the top of this forum. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Apr 10th, 2007, 3:36 AM	#6
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Look at your code again. The number you enter (testscore [i]) is not getting one added to it. The COUNTER (i) is getting one added to it. Programs run until they complete, then terminate. If you run your program from the command line, then the window belongs to command.exe. When your program completes, command.exe will put out another prompt in the same window. Your output will still be showing. If you run your program in its own window (double-clicking its icon, say), then it will terminate and the window will close. If the IDE (if you have one) provides the window, then IT will stay open, but if it spawns a window specifically for that execution, the window will close. Note that the key word is "terminate". You may add an input statement to the end of your program so that it doesn't terminate until you provide it input. It'll sit there and wait for that, giving you plenty of time to look. You can use "cin.get ()." You will need to clear the input before "cin.get ()" in case your user has pounded in some extraneous stuff. You can use cin.sync (), although there is some controversy regarding its standardized applicability to a basic_istream, or you may use cin.ignore (). See your documentation. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

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Apr 9th, 2007, 9:19 PM	#3
SonicReducer Newbie Join Date: Mar 2007 Posts: 7 Rep Power: 0	Thanks, I can compile the program now. But my question was really about the code. i equals 0, if it's less than MAX add 1? So if I typed in 22 it would become 23? Wouldn't that mess things up? Also, when I run the program it closes immeadiately after I've entered the 3 numbers, so any number that it puts out, I can't see. How can I fix this?

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Programming Forums > Application Development > C++

For Loops in this Code