program in C read txt file = find min, max, avg - c

Question

I need to write a program that opens a txt file and lists how many numbers are there (e.g. there are 25 numbers below) and then lists which number is the largest (max) and which is the smallest (min). The program then makes an average of these numbers.
So far, my program only write how many numbers I got there. When I try to make the formula to the maximum, I simply stop and can't move.
Can you help me? How do I do that by reading the rows and evaluating the largest number?
#include <stdio.h>
FILE *input;
int open()
{
if ((input = fopen("data.txt", "r")) == NULL)
{
printf("Error! opening file");
return 0;
}
}
int rows_reading ()
//Here i dont know what to do
{
input = fopen ("data.txt", "r");
}
void main ()
{
char c;
int linesCount = 0;
float max, min;
float a;
float n;
int count = 0;
input = fopen ("data.txt", "r");
while ((c = fgetc(input)) !=EOF)
{
if(c =='\n')
linesCount++;
} // this works
while ((c = getc(input)) !=EOF)
{
for (a = 0; a < count; a++){
if (a > max)
max = a;
}
} //this not work
printf("In file is %d numerical values. Max value is %d"linesCount, max);
return ;
} ```

Answer 1

Hints only since it's classwork and you'll become a better developer if you nut it out yourself :-)
The idea is to scan all the numbers and remember which was the largest and smallest. For the average, you also need to accumulate a sum of all those number along with the count.
For example, consider the following pseudo-code:
def getMinMaxAvg(inputFile):
set sum, count, smallest, largest all to zero
set value to inputFile.getNumber()
if none available, return error indication
while true
if count is zero or value is less than smallest:
set smallest to value
if count is zero or value is greater than largest:
set largest to value
add value to sum
add one to count
set value to inputFile.getNumber()
if none available, return (smallest, largest, sum / count)
That's basically the flow you need. The first important thing here is the inputFile.getNumber(), the thing that gets your numbers. Your use of fgetc will input single characters, you'll probably want to use fscanf with the "%d" specifier, so you can input integers.
Just make sure you check the return value to ensure it worked okay:
int myInt; FILE *fileHandle = fopen(...);
if (fscanf(fileHandle, "%d", &myInt) != 1)
// Did not scan properly, needs to be handled.
// Now, myInt contains your value.

Answer 2

You're reading your file character by character, which isn't a good way to read numbers. If the file contains the number "137" you will read '1', then '3', then '7'. It works for counting lines since you can just count the number of '\n' characters, which you're doing.
Does the file contain a list of numbers, one number per line? If so, you should use fgets to read the file one line at a time. Then you can use atoi to convert the string into an integer and look for the max, min, etc. One gotcha that you have to look out for us that fgets will store the \n in the string it returns, so you may need to remove it.
If your file contains numbers separated by spaces then you might consider fscanf, which may work too for lines...? Not really sure about that since it's been ages since I used fscanf.