Question

Is there a way to “bulk evaluate” the contents of an array in C++? For example, let int numbers[10]={23,42,12,42,53,10,0,0,0,0}. Is there a way to loop through each element in the array and check whether the element meets a specified condition?

In short, I’d like to be able to do something like:

if(every element in the array meets arbitrary condition)
do this

or

if(array element from m to array element n==something)
do this

For small arrays, I know I could use something like: if(numbers[0]==blabla) && if(numbers[n]==blabla), then do this, but obviously this is not a realistic solution when it comes to evaluating very large arrays.

Answer 1

” if(every element in the array meets arbitrary condition) do this ”
with STL:

bool IsOdd (int i) 
{
  return ((i%2)==1);
}
  //...
{
  vector<int> myvector;
  vector<int>::iterator it;

  myvector.push_back(2);
  myvector.push_back(4);
  myvector.push_back(6);
  myvector.push_back(8);

  it = find_if (myvector.begin(), myvector.end(), IsOdd);
  if (it == myvector.end())
    cout<< "No Odd numbers";
  }

” if(every element in the array meets arbitrary condition) do this ”
without STL

numbers[10]={2,4,6,8,10,12,14,16,18,20}
bool oddExist=false;
for (int i =0;i<10;++i)
  {
     if ( numbers[i]%2 )
     {                      //added
       oddExist=true;     
       break;               //added  for efficiency, was not in 
     }                      //        first post. 
  }
      if (!oddExist)
        cout<< "No Odd numbers";

“if(array element from m to array element n==something) do this”
with STL

void printNumber (int i) 
{
  cout  << i;
}

  // ... 

  vector<int> myvector;
  myvector.push_back(10);
  myvector.push_back(20);
  myvector.push_back(30);
  myvector.push_back(40);

  for_each (myvector.begin(), myvector.end(), printNumber);

“if(array element from m to array element n==something) do this”
without STL

numbers[10]={2,4,6,8,10,12,14,16,18,20}

for (int i =0;i<10;++i)
   cout << numbers[i];