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need a little help with arrays

Posts: 168Member
Iv been trying for a while now to learn C++, but it seems and inpossible task. I have a few questions about the following code.

What is going on with hits[10] suddenly having letters and crap inside it like r, and i?
And whats all the dividing about (n / 10)? Or the last line of code return rand() % n; correct me if IM wrong, but than n is the functions n and not the data entered my me with cin>> correct? Anyway I fill like shooting myself trying to learn this programming language. IM in the fifth chapter of C++ without fear. The code is below.

#include
#include
#include
#include
using namespace std;

int rand_0toN1(int n);

int hits[10];

int main()
{
int n;
int i;
int r;

srand(time(NULL)); // Set seed for random numbers.

cout << "Enter number of trials to run and press ENTER: ";
cin >> n;

// Run n trials. For each trial, get a number from 0 to 9
// and then increment the corresponding element in the
// hits array.

for (i = 1; i <= n; i++)
{
r = rand_0toN1(10);
hits[r]++;
}

// Print all the elements in the hits array, along with
// the ratio of hits to the EXPECTED hits (n / 10).

for (i = 0; i < 10; i++)
{
cout << i << ": " << hits[i] << " Accuracy: ";
cout << static_cast<double>(hits[i]) / (n / 10) << endl;
}

return 0;
}

// Random 0-to-N1 Function.
// Generate a random integer from 0 to N-1.
//
int rand_0toN1(int n)
{
return rand() % n;
}

• Posts: 1,444Member
: Iv been trying for a while now to learn C++, but it seems and inpossible task. I have a few questions about the following code.
:
: What is going on with hits[10] suddenly having letters and crap inside it like r, and i?
[blue]
See the comment below.[/blue]

: And whats all the dividing about (n / 10)? Or the last line of code return rand() % n; correct me if IM wrong, but than n is the functions n and not the data entered my me with cin>> correct?
[blue]
Yes. The 'n' in rand_0toN1() is local to that function.
[/blue]
Anyway I fill like shooting myself trying to learn this programming language. IM in the fifth chapter of C++ without fear. The code is below.
[code]
: #include
: #include [blue]//C++ should be [/blue]
: #include [blue]//[/blue]
: #include [blue]//[/blue]
: using namespace std;
:
: int rand_0toN1(int n);
:
: int hits[10];
:
: int main()
: {
: int n;
: int i;
: int r;
:
: srand(time(NULL)); // Set seed for random numbers.
:
: cout << "Enter number of trials to run and press ENTER: ";
: cin >> n;
:
: // Run n trials. For each trial, get a number from 0 to 9
: // and then increment the corresponding element in the
: // hits array.
:
: for (i = 1; i <= n; i++)
: {
[blue]// Here we choose a random number and
// use it as an index into hits[]. So if(r==3),
// we access hits[3]. If(r==7), we access hits[7].[/blue]
: r = rand_0toN1(10);
: hits[r]++;
: }
:
: // Print all the elements in the hits array, along with
: // the ratio of hits to the EXPECTED hits (n / 10).
:
: for (i = 0; i < 10; i++)
: {
: cout << i << ": " << hits[i] << " Accuracy: ";
: cout << static_cast<double>(hits[i]) / (n / 10) << endl;
: }
:
: return 0;
: }
:
: // Random 0-to-N1 Function.
: // Generate a random integer from 0 to N-1.
: //
: int rand_0toN1(int n)
: {
: return rand() % n;
: }
[/code]
• Posts: 5Member
HELLO, I AM HAVING THE SAME PROBLEM WITH GENERATING COMBINATIONS, IF ANYONE HELPS U FIX THIS, PLEASE EMAIL ME AT [email protected]
thanxs

Iv been trying for a while now to learn C++, but it seems and inpossible task. I have a few questions about the following code.
: :
: : What is going on with hits[10] suddenly having letters and crap inside it like r, and i?
: [blue]
: See the comment below.[/blue]
:
: : And whats all the dividing about (n / 10)? Or the last line of code return rand() % n; correct me if IM wrong, but than n is the functions n and not the data entered my me with cin>> correct?
: [blue]
: Yes. The 'n' in rand_0toN1() is local to that function.
: [/blue]
: Anyway I fill like shooting myself trying to learn this programming language. IM in the fifth chapter of C++ without fear. The code is below.
: [code]
: : #include
: : #include [blue]//C++ should be [/blue]
: : #include [blue]//[/blue]
: : #include [blue]//[/blue]
: : using namespace std;
: :
: : int rand_0toN1(int n);
: :
: : int hits[10];
: :
: : int main()
: : {
: : int n;
: : int i;
: : int r;
: :
: : srand(time(NULL)); // Set seed for random numbers.
: :
: : cout << "Enter number of trials to run and press ENTER: ";
: : cin >> n;
: :
: : // Run n trials. For each trial, get a number from 0 to 9
: : // and then increment the corresponding element in the
: : // hits array.
: :
: : for (i = 1; i <= n; i++)
: : {
: [blue]// Here we choose a random number and
: // use it as an index into hits[]. So if(r==3),
: // we access hits[3]. If(r==7), we access hits[7].[/blue]
: : r = rand_0toN1(10);
: : hits[r]++;
: : }
: :
: : // Print all the elements in the hits array, along with
: : // the ratio of hits to the EXPECTED hits (n / 10).
: :
: : for (i = 0; i < 10; i++)
: : {
: : cout << i << ": " << hits[i] << " Accuracy: ";
: : cout << static_cast<double>(hits[i]) / (n / 10) << endl;
: : }
: :
: : return 0;
: : }
: :
: : // Random 0-to-N1 Function.
: : // Generate a random integer from 0 to N-1.
: : //
: : int rand_0toN1(int n)
: : {
: : return rand() % n;
: : }
: [/code]
: