Calculating mean of an array - c++

Question

Hello I'm having issues calculating the mean of in my function, the program compiles however I don't get the intended answer of 64.2 to print out and instead get a random set of integers and characters.
This is not the entirety of the code but only the appropriate variables and functions.
// main function and prototyping would be here
int size=0;
float values[]={10.1, 9.2, 7.9, 9.2, 13.0, 12.7, 11.3};
float mean(float values[], int size)
{
float sum = 0;
float mean = 0;
for (size = 0; size > 7; size++)
{
sum += values[size];
mean = sum / 7;
}
return mean;
}

Answer 1

Change your loop like so:
for (size = 0; size < 7; size++)
{
sum += values[size];
}
mean = sum / 7;
Your terminating condition for for loop isn't right.
Move the mean out of for loop.

Answer 2

for (size = 0; size > 7; size++)
Since size is initialized as 0, and it is incremented by 1, it becomes 1 at the end of the first iteration and fails the test (it is not > 7). Thus, it immediately exits the loop.
Secondly, you calculate mean inside the loop when you should calculate it after the loop is complete. Theoretically, you should get a correct value since you redo it as the mean of the sums to that point in the loop, but it is a waste of time. You also wipe out size by redefining it.
float mean(float values[], int size)
{
float sum = 0;
float mymean = 0;
for (int i = 0; i < size; i++)
{
sum += values[i];
}
mymean = sum / size;
return mymean;
}

Answer 3

Why is the test size > 7 there? Expecting your initial value to have an unusually large value of zero? It's likely that you mean size < 7, though using arbitrary magic numbers like that is trouble.
What you probably want is:
float mean(float* values, int size)
{
float sum = 0;
for (int i = 0; i < size; ++i)
sum += values[i];
return sum / size;
}
To be more C++ you'd want that signature to be:
float mean(const float* values, const size_t size)
That way you'd catch any mistakes with modifying those values.