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question:
Find the minimum and maximum element in an array using functions.
error I am getting:
segmentation fault

What I have tried:

C++
#include<stdio.h>
int max(int a[],int n)         
{
    int i,j,max;         
    for(i=0;i<n;i++)
    for(j=i+1;j<n;j++)
    if(a[i]>a[j])
    max=a[i];
    else
    max=a[j];
    return max;
}
int min(int a[],int n)                
{
    int i,j,min;
    for(i=0;i<n;i++)
    for(j=i+1;j<n;j++)
    if(a[i]<a[j])
    min=a[i];
    else
    min=a[j];
    return min;
}
int main()
{
   int n,a[n],i;
   scanf("%d",&n);
   printf("Enter the elements in to the array");
   for(i=0;i<n;i++)
   scanf("%d",&a[i]);
   printf("%d    %d",max(a,n),min(a,n));
   return 0;
}
Posted
Updated 30-Apr-21 0:49am

This line :
C++
int n,a[n],i;
will not compile. How is the compiler to know the value of n? You have to either pre-define a maximum number of values or dynamically allocate the array.

Also, it is a bad idea to name functions or variables min and max because there are macros with those names so collisions can arise. You should call the functions something like GetMin and GetMax and the variables minValue and maxValue or something similar. You can't have a variable and a function with the same name either.
   
Comments
OriginalGriff 30-Apr-21 4:23am
   
Perhaps surprisingly, it will compile in some systems, because "n" is given a default value of 0, and C does not check for uninitialized variables anyway.

It's probably the problem, because it allocates a zero length array which means I have no idea what the array is going to end up pointing to without using his debugger, but ... it'll compile!
Rick York 30-Apr-21 4:29am
   
Yes, you are right. It would probably be best if it didn't compile so the issue would be readily apparent.
_-_-_-me 30-Apr-21 10:17am
   
When I debug,I got bus error.
but when I declare the array a after scanf() function , I got no error .
OriginalGriff 30-Apr-21 10:23am
   
Yes - because by then, "n" has a value, so the array is created with the correct number of elements.

Thirty seconds with the debugger, and you would have seen that!
Compiling does not mean your code is right! :laugh:
Think of the development process as writing an email: compiling successfully means that you wrote the email in the right language - English, rather than German for example - not that the email contained the message you wanted to send.

So now you enter the second stage of development (in reality it's the fourth or fifth, but you'll come to the earlier stages later): Testing and Debugging.

Start by looking at what it does do, and how that differs from what you wanted. This is important, because it give you information as to why it's doing it. For example, if a program is intended to let the user enter a number and it doubles it and prints the answer, then if the input / output was like this:
Input   Expected output    Actual output
  1            2                 1
  2            4                 4
  3            6                 9
  4            8                16
Then it's fairly obvious that the problem is with the bit which doubles it - it's not adding itself to itself, or multiplying it by 2, it's multiplying it by itself and returning the square of the input.
So with that, you can look at the code and it's obvious that it's somewhere here:
C#
int Double(int value)
   {
   return value * value;
   }

Once you have an idea what might be going wrong, start using the debugger to find out why. Put a breakpoint on the first line of the method, and run your app. When it reaches the breakpoint, the debugger will stop, and hand control over to you. You can now run your code line-by-line (called "single stepping") and look at (or even change) variable contents as necessary (heck, you can even change the code and try again if you need to).
Think about what each line in the code should do before you execute it, and compare that to what it actually did when you use the "Step over" button to execute each line in turn. Did it do what you expect? If so, move on to the next line.
If not, why not? How does it differ?
Hopefully, that should help you locate which part of that code has a problem, and what the problem is.
This is a skill, and it's one which is well worth developing as it helps you in the real world as well as in development. And like all skills, it only improves by use!
   
Comments
_-_-_-me 30-Apr-21 8:52am
   
Thank you for the information.
I will learn how to debug the program
OriginalGriff 30-Apr-21 10:22am
   
Good idea - learn while you are playing will little bits of code - then when you move on to the complicated stuff, you have the skills ready to use.

It's a lot harder to learn with "real world" code than it is with the bite-sized code you are currently working on!
Here you are a working (albeit reduced) version of the program.
Note you don't need two nested loops to find out the max (as well min).
C
#include<stdio.h>

int max(int a[],int n)
{
    int max = a[0]; // this assumes the array having, at least 1 element (make it more robust)

    for (int i=1; i<n; ++i)
      if ( max < a[i])
        max = a[i];

    return max;
}

int main()
{
   int n;
   printf("Enter the number of elements of the array ");
   scanf("%d", &n);
   printf("\nEnter the elements in to the array ");

   int a[n];
   for(int i=0; i<n; i++)
    scanf("%d",&a[i]);

   printf("the maximum is %d\n",max(a,n));
   return 0;
}
   
Comments
_-_-_-me 30-Apr-21 10:18am
   
Do we have to only declare the array after the scanf() function in this case?
CPallini 30-Apr-21 10:30am
   
Yes, you have to, because, as others already pointed out, before the scanf execution, the value of 'n' (that is the dimension of your array) is 'unpredictable'.
Note: you are dynamically allocating memory on the stack.

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