﻿ C - Compute the average value of the elements in a queue

# C Exercises: Compute the average value of the elements in a queue

## C Queue: Exercise-8 with Solution

Write a C program to compute the average value of the elements in a queue.

Sample Solution:

C Code:

``````#include <stdio.h>

#define MAX_SIZE 100

int queue[MAX_SIZE];
int front = -1, back = -1;

// Function to insert an element into the queue
void enqueue(int item) {
if (back == MAX_SIZE - 1) {
printf("Error: Queue is full\n");
return;
}
if (front == -1) {
front = 0;
}
back++;
queue[back] = item;
}

// Function to remove an element from a queue
int dequeue() {
if (front == -1 || front > back) {
printf("Error: Queue is empty\n");
return -1;
}
int item = queue[front];
front++;
return item;
}

// Function to compute the average of elements in a queue
float average() {
if (front == -1 || front > back) {
printf("Error: Queue is empty\n");
return -1.0;
}
float sum = 0;
int count = 0;
for (int i = front; i <= back; i++) {
sum += queue[i];
count++;
}
float result = sum/count;
return result;
}
// Function to display the elements in the queue
void display() {
printf("Queue elements are: ");
for (int i = front; i <= back; i++) {
printf("%d ", queue[i]);
}
printf("\n");
}
int main() {
// Insert some elements into the queue.
enqueue(1);
enqueue(2);
enqueue(3);
enqueue(4);
enqueue(5);
// Display the elements in the queue.
display();
// Find the sum of the elements in the queue.
float avg = average();
printf("Average of the elements in the queue is: %f\n", avg);
printf("\nRemove 2 elements from the said queue:\n");
dequeue();
dequeue();
// Display the elements in the queue.
display();
avg = average();
printf("Average of the elements in the queue is: %f\n", avg);
printf("\nInsert 3 more elements:\n");
enqueue(300);
enqueue(427);
enqueue(519);
// Display the elements in the queue.
display();
avg = average();
printf("Average of the elements in the queue is: %f\n", avg);
return 0;;
}
```
```

Sample Output:

```Queue elements are: 1 2 3 4 5
Average of the elements in the queue is: 3.000000

Remove 2 elements from the said queue:
Queue elements are: 3 4 5
Average of the elements in the queue is: 4.000000

Insert 3 more elements:
Queue elements are: 3 4 5 300 427 519
Average of the elements in the queue is: 209.666672
```

Flowchart:

C Programming Code Editor:

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﻿

## C Programming: Tips of the Day

C Programming - How do you pass a function as a parameter in C?

Declaration

A prototype for a function which takes a function parameter looks like the following:

```void func ( void (*f)(int) );
```

This states that the parameter f will be a pointer to a function which has a void return type and which takes a single int parameter. The following function (print) is an example of a function which could be passed to func as a parameter because it is the proper type:

```void print ( int x ) {
printf("%d\n", x);
}
```

Function Call

When calling a function with a function parameter, the value passed must be a pointer to a function. Use the function's name (without parentheses) for this:

```func(print);
```

would call func, passing the print function to it.

Function Body

As with any parameter, func can now use the parameter's name in the function body to access the value of the parameter. Let's say that func will apply the function it is passed to the numbers 0-4. Consider, first, what the loop would look like to call print directly:

```for ( int ctr = 0 ; ctr < 5 ; ctr++ ) {
print(ctr);
}
```

Since func's parameter declaration says that f is the name for a pointer to the desired function, we recall first that if f is a pointer then *f is the thing that f points to (i.e. the function print in this case). As a result, just replace every occurrence of print in the loop above with *f:

```void func ( void (*f)(int) ) {
for ( int ctr = 0 ; ctr < 5 ; ctr++ ) {
(*f)(ctr);
}
}
```

Ref : https://bit.ly/3skw9Um