为什么数组不在这里打印出来？ (c++)

Question

The array I have is

int age[5] = {11,2,23,4,15}

but it does not print out 11,2,23,4, 15 .

#include <iostream>
#include <array>

using namespace std;

int main() {
  int age[5] = {11,2,23,4,15};
  
  cout << age[5] << endl;
}

Answer 1

The name of the array is not age[5] .

The name of the array is age .

The expression age[5] represents the array's sixth element, which does not exist.

In fact, there is no built-in logic for printing a whole array in a formatted manner, so even cout << age << endl is not correct.

If you want to print the array, do it element-by-element in a loop.

Answer 2

Arrays are 0-indexed. In your example, the valid indexes are 0..4. You are trying to print a single int from age[5] , which is out of bounds.

You need to loop through the indexes of the array, eg:

#include <iostream>
using namespace std;

int main() {
  int age[5] = {11,2,23,4,15};
  
  for(int i = 0; i < 5; ++i) {
      cout << age[i] << " ";
  }
  cout << endl;
}

Alternatively:

#include <iostream>
#include <array>
using namespace std;

int main() {
  array<int, 5> age{11,2,23,4,15};
  
  for(int val : age) {
      cout << val << " ";
  }
  cout << endl;
}