Finding min and max value in a random array - c++

Question

Working on an assignment that requires me to put in some functions (finding max/min value, sum and average value of random numbers in an array), I've managed to complete all of them but for min value I'm getting a value of -2145379808. I'm not sure where I've messed up and I would appreciate the help.
Code so far:
#include <cstdlib>
#include <iostream>
#include <ctime>
using namespace std;
int main(int argc, char** argv) {
{
cout << "Enter array size " << endl;
}
float avg;
float sum;
int size;
cin >> size;
int array[size];
int max = array [0];
int min = array [0];
srand((unsigned)time(NULL));
for (int i = 1; i < size + 1; i++)
{
array[i] = 1+rand()%100 ;
sum += array[i];
cout << "number " << i << " = "<< array[i] << endl;
}
for (int x = 1; x < size; x++){
if (array[x] > max){
max = array[x];
}
if (array[x] < min){
min = array[x];
}
}
cout << "\nmax = " << max << endl;
cout << "\nmin = " << min << endl;
cout << "\nsum = "<< sum << endl;
cout << "\navg = " << sum / size << endl;
return 0;
}

Answer 1

Setting max and min to the uninitialised element of array is never going to end well. On this note, you also need to initialise sum. You may as well remove avg since you don't use it.
You need to set max and min to the first element of array once you know what it is. Crudely, you could set max to std::numeric_limits<int>::min() and min to std::numeric_limits<int>::max().
Note also that the bounds of array are array[0] to array[size - 1]. Therefore you need to revisit the indexing in your loops.
Then once you have it working, bin it, and use std::vector<int>, and things like minmax_element: http://en.cppreference.com/w/cpp/algorithm/minmax_element

Answer 2

The problem is in following lines:
float avg;
float sum;
...
int max = array [0];
int min = array [0];
Because at this point the value at array [0] are garbage value.
To correct your code change this line as following (also include climits header file). Also, change loops index accordingly:
float avg = 0;
float sum = 0;
...
int max = INT_MIN;
int min = INT_MAX;
Following is corrected code(some changes made for optimization). See it working here:
#include <cstdlib>
#include <iostream>
#include <ctime>
#include <climits>
using namespace std;
int main(int argc, char** argv) {
{
cout << "Enter array size " << endl;
}
float sum = 0;
int size;
cin >> size;
int array[size];
int max = INT_MIN;
int min = INT_MAX;
srand((unsigned)time(NULL));
for (int i = 0; i < size; i++)
{
array[i] = 1+rand()%100 ;
sum += array[i];
cout << "number " << i << " = "<< array[i] << endl;
if (array[i] > max){
max = array[i];
}
if (array[i] < min){
min = array[i];
}
}
cout << "\nmax = " << max << endl;
cout << "\nmin = " << min << endl;
cout << "\nsum = "<< sum << endl;
cout << "\navg = " << sum / size << endl;
return 0;
}

Answer 3

To insure your max and min are initialized correctly, C++ provides std::numeric_limits for all types. They each have max() and min() member functions to return the max and min value for the type. In any code you want to find a maximum and minimum, you want to first initialize your maximum to the minimum of the type and vice versa. That way any value will be larger than your min and smaller than your max.
You do that with std::numeric_limits similar to:
int min = std::numeric_limits<int>::max()
int max = std::numeric_limits<int>::min()
Let me know if you have more questions.