Question

The goal of this project is to practice (Write a C Program) with a function that one of its parameter is a function.The prototype of this function is:

void func ( float (*f)(float*, int), float* a, int length);

This means the function: func has three parameters:

• float (*f)(float*, int): This parameter itself is a function: f that has two parameters and returns a floating-point number. In the body of the function: func we call the function: f with its arguments to be the second and third parameters of the function: func (i.e. a, and length). The parameters:
  • float*: This represents an array of type: float.
  • int: A parameter of a simple type to be used for the size of the array.
• float* a: This represents an array of type: float.
• int length: A parameter of a simple type to be used for the size of the array.

We then define three functions with the following prototypes:

float sum(float* a, int length): Returns the sum of all the elements of the array: a.

float product(float* a, int length): Returns the product of all the elements of the array: a.

float average(float* a, int length): Returns the average of all the elements of the array: a.

For the function: main write code for the following comments.

int main (){

//Declare (define) these variables.

  float* a;

int n, …; //You need to define more variables.

//Ask the user how numbers

//The user enters a positive integer. Give it to variable: n

// Use the built-in function: malloc to allocate n consecutive location of

// type float for variable: a

// Ask the user to enter n decimal numbers and give them to array: a. Do not

// forget, you need to use: & to read to an element of an array.

// Prompte the user the following message:

printf("Enter 1,2,or 3 to calculate the sum, product, or average of the numbers respectively:");

// Code based on the number the user enters. If the number entered is:

// 1 then call func with the argument: sum and two more arguments a and n.

// 2 then call func with the argument: product and two more arguments a and n.

// 3 then call func with the argument: average and two more arguments a and n.

// An integer other than 1, 2, or 3 then output the use that only numbers 1,

// 2, or 3 should be entered.

return 0;

}

The following is four sample dialogs of my program. Note that the boldfaced lines are not from the execution of the program.

Sample dialog 1: The output is the addition of numbers.

How many numbers? 3

Enter 3 number: 2.2 3.3 4.4

Enter 1, 2, or 3 to calculate the sum, product, or average of the numbers respectively: 1

The result is: 9.90

Sample dialog 2: The output is the product of numbers.

How many numbers? 3

Enter 3 number: 2.2 3.3 4.4

Enter 1, 2, or 3 to calculate the sum, product, or average of the numbers respectively: 2

The result is: 31.94

Sample dialog 3: The output is the avarage of numbers.

How many numbers? 3

Enter 3 number: 345.2 -345.5 22.4

Enter 1, 2, or 3 to calculate the sum, product, or average of the numbers respectively: 3

The result is: 7.37

Sample dialog 4: The output is an error message because the user entered 4.

How many numbers? 3

Enter 3 number: 1 2 3

Enter 1, 2, or 3 to calculate the sum, product, or average of the numbers respectively: 4

Only enter 1, 2, or 3

Answer:

#include <stdio.h>

#include <stdlib.h>

void func ( float (*f)(float*, int), float* a, int length);

float sum(float* a, int length);

float product(float* a, int length);

float average(float* a, int length);

Answer 1

C code

#include <stdio.h>
#include <stdlib.h>

void func ( float (*f)(float*, int), float* a, int length){
   printf("The result is: %.2f\n",(*f)(a,length));
}

float sum(float* a, int length){
   float total = 0;
   int i;
   for(i=0;i<length;i++){
       total += a[i];
   }
   return total;
}

float product(float* a, int length){
   float prod = 1;
   int i;
   for(i=0;i<length;i++){
       prod *= a[i];
   }
   return prod;
}

float average(float* a, int length){
   return sum(a,length)/length;
}

int main(){
   int length,i,choice;
  
   printf("How many numbers? ");
   scanf("%d",&length);
  
   printf("Enter %d number: ",length);
   float* a = (float*) malloc(length*(sizeof(float)));
   for(i=0;i<length;i++){
       scanf("%f",&a[i]);
   }
  
   printf("Enter 1, 2, or 3 to calculate the sum, product, or average of the numbers respectively: ");
   scanf("%d",&choice);
  
   if(choice == 1){
       func(&sum , a , length);
   }
   else if(choice == 2){
       func(&product , a , length);
   }
   else if(choice == 3){
       func(&average , a , length);
   }
   else{
       printf("Error: Invalid choice");
   }
   free(a);
   return 0;
}