C++ expression must be an lvalue or a function designator - c++

Question

Here is my code I have looked up what to do multiple times and still haven't figured out what to do.
It keeps giving me this error: C++ expression must be an lvalue or a function designator with the part of the code :
avg_score = (float)*&get_average_score(score_1, score_2, score_3);`
how can i fix the error?
the original error was cannot convert a void to a float
avg_score = get_average_score(score_1, score_2, score_3);
how can i fix the error?`
#include <iostream>
#include <cstdlib>
#include <iomanip>
#include <ctime>
using namespace std;
void print_scores(int score_1, int score_2, int score_3);
void get_average_score(int score_1, int score_2, int score_3);
int main()
{
srand(time(NULL));
int score_1, score_2, score_3;
float avg_score;
score_1 = rand() % 21 + 20;
while (score_1 % 2 == 0)
{
score_1 = rand() % 21 + 20;
}
score_2 = rand() % 21 + 20;
score_3 = rand() % 21 + 20;
print_scores(score_1, score_2, score_3);
avg_score = (float)*&get_average_score(score_1, score_2, score_3);
cout << fixed << setprecision(1);
cout << "Average score = " << avg_score <<
endl;
return 0;
}
void print_scores(int score_1, int score_2, int score_3)
{
cout << "score 1 = " << score_1 << endl << "score 2 = " << score_2 << endl
<< "score 3 = " << score_3 << endl;
}
void get_average_score(int score_1, int score_2, int score_3)
{
(float)(score_1 + score_2 + score_3) / (float)3;
}

Answer 1

Your first mistake lies in the fact that you are trying to get a function that does not return a value to return a value. You've tried to reference a pointer *& which is not how you should be handling this as
1) you've tried to reference a pointer but instead you've done it on a function
2) you want a value, not a pointer so its the wrong approach.
If you need to use pointers (because thats the task at hand) then what you need to do is pass a reference to avg_score into your function.
void get_average_score(float * avg_score, int score_1, int score_2, int score_3)
{
*avg_score = (score_1 + score_2 + score_3) / 3.0;
}
and call it in main with:
get_average_score(&avg_score, score_1, score_2, score_3);
and dont forget to update the header declaration:
void get_average_score(float * avg_score, int score_1, int score_2, int score_3);
If you don't have to use pointers the easiest fix is to actually return a value.
Declare the function as type float :
float get_average_score(int score_1, int score_2, int score_3);
and edit the get_average_score function to be:
float get_average_score(int score_1, int score_2, int score_3)
{
return (score_1 + score_2 + score_3) / 3.0;
}
and get rid of (float)*& from main.
This means your function will return a float value that will be stored in avg_score on return.
Also note, by changing the denominator to 3.0 instead of 3 you don't need to don't need to type cast the result as a float.
Your coding style does come off as a little basic (which is ok, everyone has to start somewhere) but you have room for improvement, so take the time to learn now rather than struggling later (trust me it makes life easy in the long run).
Rather than making a function that will only work when you are averaging 3 numbers why not make a more modular function that would work for as many numbers as you want!
Try learning how to use vectors! If you're coming from C its kinda like an array but can be dynamically allocated i.e. any size you want.
Have a look around the net for some tutorials on what vectors are and how to use them.
I won't write out the code for this because you should learn how to do it your self (trust me you'll understand it better) but basically using a vector of int's std::vector<int> you can iterate through them all and add each element together and then at the end divide by the total number of elements (the number of iterations you do) to get your average!
**obviously theres a limit but thats a limit of your computer... *