What the code writes step by step in c++

Question

Hello, can somebody please help me with this code? It's a school assignment. The question is:

After the code runs, what value will belong to the following keys in counter map?

The code is the following:

map <int, unsigned int> counter={{3,2}, {25,4}, {34,3}, {21,1}, {4,2}, {26,0}, {54,0}};
vector <int> rawValues{3,5,4,25,43}
for (int v: rawValues)
counter.insert({v,1});
for (int value : {23,24,25,54,34,23,23,34,43,21,54})
counter[value];

The keys whose value we are looking for are the following:
3:
5:
12:
23:
25:
26:
43:
54:

Can somebody break it down please step by step? Thank you very much!

Answer 1

You can read about the map data structure, for example here:

https://www.scaler.com/topics/cpp/map-in-cpp/

A map has pairs of key and value. Keys are unique and cannot be changed (only deleted). The values associated with a certain key, can be updated in the map.

I really recommend to try ChatGPT. You can ask it to "explain this c++ code step by step" and it will analyse the code in detail. You can get amazing results even with ChatGPT 3.5 which is the free version.

https://chat.openai.com
(there are also mobile apps)

Answer 2

you can run the code and find out for yourself

https://code.sololearn.com/cJQes6YSP5TM/?ref=app

Answer 3

Certainly! Let's break down the code and determine the values for each key in the `counter` map after the given operations:

```cpp
#include <iostream>
#include <map>
#include <vector>

int main() {
std::map<int, unsigned int> counter = {{3, 2}, {25, 4}, {34, 3}, {21, 1}, {4, 2}, {26, 0}, {54, 0}};
std::vector<int> rawValues{3, 5, 4, 25, 43};

for (int v : rawValues)
counter.insert({v, 1});

for (int value : {23, 24, 25, 54, 34, 23, 23, 34, 43, 21, 54})
counter[value];

// Output the final values in the counter map
for (const auto& entry : counter) {
std::cout << "Key: " << entry.first << ", Value: " << entry.second << std::endl;
}

return 0;
}
```

Now, let's analyze the code step by step:

1. The `counter` map is initialized with certain key-value pairs.
2. The `rawValues` vector contains values that will be inserted into the `counter` map with a value of `1` for each.

Let's go through the keys you provided:

- 3: After the insertion, it will have a value of `1`.
- 5: After the insertion, it will have a value of `1`.
- 12: Not present in either initialization or insertion, so the default value (0 for `unsigned int`) will be associated.
- 23: Not inserted during initialization or the first loop, so the default value (0 for `unsigned int`) will be associated.
- 25: After the insertion, it will have a value of `1`.
- 26: Not present in either initialization or insertion, so the default value (0 for `unsigned int`) will be associated.
- 43: After the insertion, it will have a value of `1`.
- 54: After the insertion, it will have a value of `1`.

After running the code, the output should be:

```
Key: 3, Value: 1
Key: 4, Value: 2
Key: 5, Value: 1
Key: 21, Value: 1
Key: 23, Value: 0
Key: 25, Value: 1
Key: 26, Value: 0
Key: 34, Value: 3
Key: 43, Value: 1
Key: 54, Value: 1
```

So, the values for the specified keys are as follows:
- 3: 1
- 5: 1
- 12: 0
- 23: 0
- 25: 1
- 26: 0
- 43: 1
- 54: 1

Answer 4

Thank you all!