Program to find number of elements between two elements a and b (where a and b both are inclusive)

Issue

Given an unsorted array of size n, write a program to find number of elements between two user-defined elements a and b (where a and b both are inclusive) of a user-defined array.
Input : arr = [1, 2, 2, 7, 5, 4]
a=2 b=5
Output : 4
(The numbers are: 2, 2, 5, 4).
If a=6 b=15, then output will be 3 (The numbers are: 6, 7, 15)

I tried the following code, but for arr = [1, 3, 3, 9, 10, 4] and for a=9 & b=12, it is showing the output:- 2. But the output should be 3. I can’t figure out the proper logic to solve the question.

``````#include <stdio.h>

int main()
{
int n,i,a,b,c=0,d=2;

printf("Enter size of array: ");
scanf("%d",&n);

printf("Enter elements of array: ");

int arr[n];

for(i=0;i<n;i++){
scanf("%d",&arr[i]);
}

printf("\nEnter lower limit element & upper limit element respectively: ");
scanf("%d %d",&a,&b);

for(i=0;i<n;i++){
if(arr[i]==a || arr[i]==b){
c++;
d=0;
}

if(arr[i]>a && arr[i]<b){
c++;
}
}

printf("Number of elements in between two elements (Both Inclusive) = %d",c+d);

return 0;
}
``````

Please suggest the logic. I will be very thankful for that.

Solution

This statement in the last for loop

``````d=0;
``````

produces a logical error.

One of approaches is to declare two variables instead of the one variable `d`.

For example

``````int lower_limit = 0, upper_limit = 0;
``````

And then in the for loop to write

``````for ( i = 0; i < n; i++ ){
if ( arr[i] >= a && arr[i] <= b ){
c++;
lower_limit |= a == arr[i];
upper_limit != b == arr[i];
}
}

c += !lower_limit + !upper_limit;
``````

Here is a demonstrative program.

``````#include <stdio.h>

int main(void)
{
int arr1[] = { 1, 2, 2, 7, 5, 4 };
size_t n = sizeof( arr1 ) / sizeof( *arr1 );

int a = 2, b = 5;

size_t count = 0;
int lower_limit = 0, upper_limit = 0;

for ( size_t i = 0; i < n; i++ )
{
if ( a <= arr1[i] && arr1[i] <= b )
{
++count;
lower_limit |= arr1[i] == a;
upper_limit |= arr1[i] == b;
}
}

count += !lower_limit + !upper_limit;

printf( "Number of elements between %d and %d is %zu\nv", a, b, count );

a = 6; b = 15;

count = 0;
lower_limit = 0; upper_limit = 0;

for ( size_t i = 0; i < n; i++ )
{
if ( a <= arr1[i] && arr1[i] <= b )
{
++count;
lower_limit |= arr1[i] == a;
upper_limit |= arr1[i] == b;
}
}

count += !lower_limit + !upper_limit;

printf( "Number of elements between %d and %d is %zu\n", a, b, count );

return 0;
}
``````

The program output is

``````Number of elements between 2 and 5 is 4
Number of elements between 6 and 15 is 3
``````