[Gabriel] 5 ways to output (traverse) elements in vector containers in C++

Hello everyone! I'm Gabriel! When we use vector to solve algorithm problems, we often need to traverse the output. For this, I have the following 5 methods: 

1. Use a range-based for loop to access elements from the vector container one by one and output them:

   std::vector<int> vec = { 1, 2, 3, 4, 5 };
   
   for (auto element : vec) {
       std::cout << element << " ";
   }
   

    

2. Use an iterator to traverse the entire vector container and output the value of each element

   std::vector<int> vec = { 1, 2, 3, 4, 5 };
   
   for (auto it = vec.begin(); it != vec.end(); ++it) {
       std::cout << *it << " ";
   }
   

    

3. Use the standard library algorithm std::for_each()to traverse the entire vector container and output the value of each element:

   std::vector<int> vec = { 1, 2, 3, 4, 5 };
   
   std::for_each(vec.begin(), vec.end(), [](int element){
       std::cout << element << " ";
   });
   

    

4. Use the initial statement in the for loop introduced by C++11 to declare a counter variable, and then use at()the function of the vector container and the counter variable to output the value of each element:

   std::vector<int> vec = { 1, 2, 3, 4, 5 };
   
   for (size_t i = 0; auto element = vec.at(i); ++i) {
       std::cout << element << " ";
   }
   

    

5. std::copy()Copies all elements in the vector container to the output stream using standard library algorithms :

   std::vector<int> vec = { 1, 2, 3, 4, 5 };
   
   std::copy(vec.begin(), vec.end(), std::ostream_iterator<int>(std::cout, " "));
   

   Note: The above examples all assume that the vector container contains integer types. If other types of elements are stored in the container, the code needs to be changed accordingly.

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