C Finding Maximum and Minimum value? [closed] - c

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In Case of Finding Maximum and minimum Value in Array. We intialize max =0 or max=temp[0];
But in case of Minimum value we doesn't require to initialize min =0 or min=temp[0]... Why?

Answer 1

max = temp[0] acts as reference point. You start comparing each element with this and if any element is greater than this, max value will be updated to that one. similarly min = temp[0] is also valid, but now algorithm will be changed and you need to compare each element if anyone is smaller than this if yes then min will be updated to that.

Answer 2

You always need to initialise variables in C before accessing them; it's undefined behaviour not to. The best thing to do, is, having checked the array length is not zero, is to initialise min / max to the zeroth element. Then loop from the first element.

Answer 3

First, you shouldn't initialize max with 0 in any case (for example, when finding maximum of array which contains all negative values if you initialize max with 0, result will always be 0).
Since for finding maximum (and minimum) you need to compare variable max (or min) with some other value, you need to initialize to temp[0] in any case to avoid comparing array elements with uninitialized variable.
I found the part of your code in another comment:
#include<stdio.h>
int main() {
int arr[3];
int i,max,min; max=min=0;
printf("Enter the value in Array \n");
for(i=1;i<=3;i++) {
scanf("%d",&arr[i]);
}
printf("\n Value of array \n");
for(i=1;i<=3;i++) { printf("%d \n",arr[i]); }
printf("\n Finding Maximum and minimum value \n");
for(i=1;i<=3;i++) {
if(arr[i]>max) max=arr[i];
if(arr[i]<min) min=arr[i];
}
printf("Max = %d \n Min = %d \n ",max,min);
getch();
}
There are few things that doesn't work:
for(i=1;i<=3;i++)
In C, indexing starts from 0, so the valid array elements are arr[0], arr[1] and arr[2], so that for loop should be
for(i = 0; i < 3; i++)
Ok, now imagine that you have in your array elements 10, 5 and 7.
You're setting min value to 0:
max=min=0;
And now you are iterating over this loop:
for(i=0;i<3;i++) {
//...
if(arr[i]<min) min=arr[i];
}
Is 10 < 0? No, it's not.
Is 5 < 0? No, it's not.
Is 7 < 0? No, it's not.
So you see, the min will never change.
To avoid this, just set it to the first element after reading the array:
for(i= 0;i < 3;i++) {
scanf("%d",&arr[i]);
}
min = max = arr[0];
Now, let's repeat our loop:
for(i=0;i<3;i++) {
//...
if(arr[i]<min) min=arr[i];
}
Is 10 < 10? No, it's not.
Is 5 < 10? Yes, it is! Set the min to the 5
Is 7 < 5? No, it's not.
Now the min is 5.
Same issue you have in your existing code with max. Imagine you enter -4, -55 and -20 for elements - max would always stay 0.