Help with queue

Using Arduino Programming Questions
1

I'm attempting to use this Queue library:

So far I'm not having any luck. Here's my stripped down code, based on this example:

#include <cppQueue.h>

typedef struct strRec {
  char  url[300];
  char  misc1[255];
} Rec;

Rec tab[2] = {
  { "https://whatever1.com", "something1" },
  { "https://whatever2.com", "something2" }
};
cppQueue  queue1(sizeof(Rec), 10, LIFO, true); 


void setup() {
  Serial.begin(115200); 
}

void loop() {
  
    // iterate through the queue
    for (int i = 0 ; i < sizeof(tab)/sizeof(Rec) ; i++)
    {
      Rec rec;
      queue1.pop(&rec);
      Serial.println("There's something in the queue!");
      Serial.println();
      Serial.print(rec.url);
      Serial.print(" ");
      Serial.print(rec.misc1);

      Serial.println();
      String url = rec.url;
      Serial.println("URL = " + url);
      
      Serial.println();
    }   

    delay(1000);
}

However this just prints gibberish to the console:

There's something in the queue! ⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮xV⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮xV⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮xV⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮xV⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮ ,⸮ URL = ⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮

Any ideas by chance?

Also, shouldn't calling pop() on the queue remove that item from the queue? Currently it isn't.

2

There is a separate example for working with strings. Perhaps that helps.

3

I saw that, and thank you, but I would like to use a struct (of strings).

4

Ah, I see you did not push() anything, so whatever you pop() is undefined.

You probably want to add something like this (taken from the example):

for (i = 0; i < sizeof(tab) / sizeof(Rec); i++) {
  Rec rec = tab[i];
  q.push(&rec);
}
5

Thank you! And oops.

My fixed code and simpler example of using the Queue library, on the off chance it's useful to someone:

#include <cppQueue.h>

typedef struct strRec {
  char  url[300];
  char  misc1[255];
} Rec;

cppQueue  queue1(sizeof(Rec), 10, LIFO, true); 

void setup() {
  Serial.begin(115200); 

  Rec test = {"http://google.com", "some stuff"};
  queue1.push(&test);

}

void loop() {  

  // iterate through the queue
  while (!queue1.isEmpty())
  {
    Rec rec;
    queue1.pop(&rec);
    Serial.println("There's something in the queue!");
    Serial.println();
    Serial.print(rec.url);
    Serial.print(" ");
    Serial.print(rec.misc1);

    Serial.println();
    String url = rec.url;
    Serial.println("URL = " + url);
    
    Serial.println();
  }   

  delay(1000);

}

This outputs:

On a sidenote that example that I used as a starting point strikes me as confusing. Why would anyone iterate the queue in that way instead of using "while (!queue1.isEmpty())"? And why does the struct "tab" exist at all?

6

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