How to find a minimum? - c

Question

I need to make a user enter the N (the number) between 7 and 12 ([7;12]). Then, I need to make the user enter the amount of numbers, which should be equal to N. Then, I need to output the sum of these numbers, find the average, min and max.
It works perfectly, except the minimum. When the count of numbers starts from 1, my program shows me that the minimum is 0. Thank you ahead...
#include <stdio.h>
int main(void) {
int i = 0;
int N;
float numbers;
float sum = 0;
float average, min, max;
printf("Choose a number between 7 and 12: ");
scanf("%d", &N);
if (N >= 7 && N <= 12) {
printf("You have chosen: %d\n", N);
printf("Now choose the amount of N numbers you have chosen: ");
for (i = 0; i < N; i++) {
numbers = N; // the numbers the user enters must be
// strictly == N
scanf("%f", &numbers);
sum = sum + numbers;
average = sum / numbers;
if (numbers < min) {
min = numbers;
}
if (numbers > max) {
max = numbers;
}
}
printf("The sum of your numbers is: %f\n The average of "
"numbers: %f\n The max: %f\n The min: %f\n",
sum, average, max, min);
}
}
The output is:
Choose a number between 7 and 12: 7
You have chosen: 7
Now choose the amount of N numbers you have chosen: 1
2
3
4
5
6
7
The sum of your numbers is: 28.000000
The average of numbers: 4.000000
The max: 7.000000
The min: 0.000000

Answer 1

Your min and max values are used uninitialized. On your platform/compiler, it appears that these are being default initialized to zero, but the C Standard does not require that.
To fix this issue, just initialize those variables (at the time of their declarations) to values that cannot be the final values (like the +/- values of the FLT_MAX constant, defined in <float.h>):
//...
float average, min = FLT_MAX, max = -FLT_MAX;
//...

Answer 2

I would go about this in a completely different fashion. Store the numbers in an array and then sort them. This is an example using integers, but it is very easy to modify for float usage.
#include <stdio.h>
// Bubble sort
void bubbleSort (int *numArray, int numElements) {
int sorted = 0, temp;
while (!sorted) {
// Set this flag here
sorted = 1;
for (int i = 0; i < numElements - 1; i++) {
// Swaps the numbers
if (numArray [i] > numArray [i + 1]) {
temp = numArray [i];
numArray [i] = numArray [i + 1];
numArray [i + 1] = temp;
sorted = 0;
}
}
}
}
float calcAverage (int numArray [], int numElements) {
float avg = 0;
for (int i = 0; i < numElements; i++) avg += numArray [i];
return avg / numElements;
}
int main() {
int numElements = 0;
// Ensure they actually enter a number!
while (numElements < 7 || numElements > 12) {
printf ("Please enter a number between 7 and 12: ");
// Input validation is always important in my opinion.
if (!scanf ("%d", &numElements)) {
printf ("ERROR: NaN value passed! ");
}
else if (numElements < 7 || numElements > 12) printf ("ERROR: Invalid number! ");
// Clear the buffer
while (getchar() != '\n');
}
printf ("You have chosen: %d.\n", numElements);
// Create our array and store our current number.
int numArray [numElements], fGood;
for (int i = 0; i < numElements; i++) {
// Reset this flag at the beginning of the loop
fGood = 0;
while (!fGood) {
printf ("Please enter value %d: ", i + 1);
// Assume it's a good value
fGood = 1;
if (!scanf ("%d", &numArray [i])) {
printf ("ERROR: Invalid value passed! ");
}
while (getchar() != '\n');
}
}
bubbleSort (numArray, numElements);
printf ("Average of entered numbers: %.2f\nMinimum value: %d\nMaximum value: %d\n", calcAverage(numArray, numElements), numArray [0], numArray [numElements - 1]);
return 0;
}