biggest

C Program To Find Largest Difference Between Two Elements of Array

Write a C program to find largest / maximum difference between two elements of an array, such that larger element or number appears after the smaller number in the array.

Note: I’m not considering time complexity in this video tutorial intentionally. We’ll have a completely dedicated video teaching about time complexity from basic. My intention in this video is to make the logic as simple and understandable as possible.

Example: Expected Output

Enter 6 integer numbers
7
9
5
6
13
2
The largest difference is 8, and its between 13 and 5.

Visual Representation

Largest Difference Between Two Elements of Array

Video Tutorial: C Program To Find Largest Difference Between Two Elements of Array

[youtube https://www.youtube.com/watch?v=XLHcpajCZyQ]

YouTube Link: https://www.youtube.com/watch?v=XLHcpajCZyQ [Watch the Video In Full Screen.]

Source Code: C Program To Find Largest Difference Between Two Elements of Array

#include<stdio.h>

#define N 6

int main()
{
    int num[N], i, big, small;

    printf("Enter %d integer numbers\n", N);
    for(i = 0; i < N; i++)
        scanf("%d", &num[i]);

    big = small = num[0];

    for(i = 1; i < N; i++)
    {
        if(num[i] > big)
            big = num[i];

        if(num[i] < small)
            small = num[i];
    }

    printf("The largest difference is %d, ", (big - small));
    printf("and its between %d and %d.\n", big, small);

    return 0;
}

Output:
Enter 6 integer numbers
7
9
5
6
13
2
The largest difference is 11, and its between 13 and 2.

Here we find biggest element in the array and smallest element in the array. Next we subtract smallest element from biggest element to get the largest different between two array elements.

Find Largest Difference, where Largest Element Appears After Smallest Number in Array

#include<stdio.h>

#define N 6

int main()
{
    int num[N], i, big, small, pos = 0;

    printf("Enter %d integer numbers\n", N);
    for(i = 0; i < N; i++)
        scanf("%d", &num[i]);

    big = small = num[0];

    for(i = 1; i < N; i++)
    {
        if(num[i] > big)
        {
            big = num[i];
            pos = i;
        }
    }

    for(i = 1; i < pos; i++)
    {
        if(num[i] < small)
            small = num[i];
    }

    printf("The largest difference is %d, ", (big - small));
    printf("and its between %d and %d.\n", big, small);

    return 0;
}

Output:
Enter 6 integer numbers
7
9
5
6
13
2
The largest difference is 8, and its between 13 and 5.

Logic To Find Largest Difference b/w Two Elements of Array, where biggest number appears after the smallest number

As per the problem statement, the smallest number in the array must be chosen from index 0 to the position where the biggest number of the array is present.

For Example: Assume that we’ve an array {1, 2, 5, 3, 0}. Here biggest element in the array is 5 and its position in the array is 2. Now we need to select smallest number in the array between the index range 0 to 2. So the smallest number will be 1.

Step 1: First we iterate through the array using a for loop and find the biggest element in the array and we also determine the index position at which this biggest number is present.

Step 2: We write another for loop and iterate from index 1 to the position where the biggest number is present. And inside for loop we select the smallest element between the range.

Step 3: Now we subtract the smallest element from step 2 with the biggest element from step 1, and we get the largest difference between two elements of an array, where biggest number appears after the smaller number in the array.

Note:
1. We initialize variables big and small to the first element of the array, because we need to have some value to compare it with other elements of the array.
2. In both the for loops we initialize i to 1, as both variables big and small is assigned with value present at index 0. So there is no point in comparing with itself, so we start the comparison from index 1. That’s the reason we initialize i to 1 in both the for loops.

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

C Program To Find First and Second Biggest Element In An Array

Lets write a C program to find first and second biggest element/number in an array, without sorting it.

Example: Expected Output

Enter 5 unique integer numbers
5
2
6
4
3
First Big: 6
Second Big: 5
array with size 5

Important Note:
This code only works for inputs which has unique integer numbers. If there are duplicate integer numbers which is biggest in the array, then it’ll show the same number for both first and second biggest element. We can fix it, but it’s out of scope of this problem statement. Just know the limitation of this code.

Ex: a[5] = {2, 4, 5, 3, 5};
In this case, both first big and second big will have value 5.

Video Tutorial: C Program To Find First and Second Biggest Element In An Array

[youtube https://www.youtube.com/watch?v=iBqz2ZmQHSE]

YouTube Link: https://www.youtube.com/watch?v=iBqz2ZmQHSE [Watch the Video In Full Screen.]

Source Code: C Program To Find First and Second Biggest Element In An Array

#include<stdio.h>

#define N 5

int main()
{
    int a[N], i, fbig, sbig;

    if(N < 3)
    {
        printf("Please have an array with at least 2 elements\n");
        return(0);
    }

    printf("Enter %d unique integer numbers\n", N);
    for(i = 0; i < N; i++)
        scanf("%d", &a[i]);

    (a[0] > a[1]) ? (fbig = a[0], sbig = a[1]) :
                    (fbig = a[1], sbig = a[0]);

    for(i = 2; i < N; i++)
    {
        if(fbig < a[i])
        {
            sbig = fbig;
            fbig = a[i];
        }
        else if(sbig < a[i])
        {
            sbig = a[i];
        }
    }

    printf("First Big: %d\nSecond Big: %d\n", fbig, sbig);

    return 0;
}

Output 1:
Enter 5 unique integer numbers
5
2
6
4
3
First Big: 6
Second Big: 5

Output 2:
Enter 5 unique integer numbers
2
4
5
7
9
First Big: 9
Second Big: 7

In above source code we’re making use of macros to assign array size.

Logic To Find First and Second Biggest In An Array

First we assign biggest of a[0] and a[1] to variable fbig and the second biggest to sbig.
1. Using if else

    if(a[0] > a[1])
    {
        fbig = a[0];
        sbig = a[1];
    }
    else
    {
        fbig = a[1];
        sbig = a[0];
    }

2. Using Ternary/Conditional Operators

    (a[0] > a[1]) ? (fbig = a[0], sbig = a[1]) :
                    (fbig = a[1], sbig = a[0]);

In both the cases the logic is same. If a[0] is greater than a[1], then value present at a[0] will be assigned to fbig, and a[1] will be assigned to sbig. If a[0] is not greater than a[1], then a[1] will be assigned to fbig and a[0] will be assigned to sbig.

for loop
Since both a[0] and a[1] are already sorted out, the comparison must start from a[2]. So we initialize the loop counter variable i to 2 and loop through until i < N and for each iteration we increment the value of i by 1.

Inside for loop
If value of fbig is less than the fetched element of the array, then we transfer the value of fbig to sbig and assign the new array element value to fbig.

Else if, the fetched element of the array is less than fbig but greater than sbig, then we assign the value of the array element to sbig.

    for(i = 2; i < N; i++)
    {
        if(fbig < a[i])
        {
            sbig = fbig;
            fbig = a[i];
        }
        else if(sbig < a[i])
        {
            sbig = a[i];
        }
    }

Once control exits for loop, we print the values present in fbig and sbig.

Explanation With Example

If int a[6] = {2, 4, 5, 7, 9, 8};
Here a[0] = 2 and a[1] = 4;
After executing below code:

    (a[0] > a[1]) ? (fbig = a[0], sbig = a[1]) :
                    (fbig = a[1], sbig = a[0]);

fbig will have a[1], which is 4.
sbig will have a[0], which is 2.

index	a[index]	sbig	fbig
2	a[2] = 5	4	5
3	a[3] = 7	5	7
4	a[4] = 9	7	9
5	a[5] = 8	8

At the end of for loop, fbig will have 9 and sbig will have 8.

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

C Program To Find Biggest Element of An Array

Lets write a C program to find biggest or the largest element in an array, without sorting the elements. And also print the position at which the biggest number is present in the array.

Example: Expected Output

Enter 5 integer numbers
5
2
6
4
3

Biggest of 5 numbers is 6, at position 3

array with size 5

Video Tutorial: C Program To Find Biggest Element In An Array

[youtube https://www.youtube.com/watch?v=Ram2KW-n0Qc]

YouTube Link: https://www.youtube.com/watch?v=Ram2KW-n0Qc [Watch the Video In Full Screen.]

Source Code: C Program To Find Biggest Element of An Array

Method 1

#include<stdio.h>

#define N 5

int main()
{
    int a[N], i, big, pos;

    printf("Enter %d integer numbers\n", N);
    for(i = 0; i < N; i++)
    {
        scanf("%d", &a[i]);

        if(i == 0 || big < a[i])
        {
            big = a[i];
            pos = i + 1;
        }
    }

    printf("\nBiggest of %d numbers is %d, at position %d.\n", N, big, pos);

    return 0;
}

Output 1:
Enter 5 integer numbers
1
3
2
5
8

Biggest of 5 numbers is 8, at position 5.

Output 2:
Enter 5 integer numbers
10
2
5
9
3

Biggest of 5 numbers is 10, at position 1.

Logic To Find Biggest Element In An Array

We ask the user to input N integer numbers. N being a Macro. In above source code N is 5. So user enters 5 integer numbers. While the user inputs numbers we check if it’s the first number input by the user. If its the first number, then we assign that first number entered by the user to variable big and assign 1 to variable pos, indicating that its the first element in the array.

Next, for each consecutive iteration of the for loop we check if the new value entered by the user is greater than the value present in variable big. If it’s true, then we assign the new value entered by the user to variable big and also update the value of pos accordingly.

Once i < N condition is false, control exits for loop and we print the value present inside variable big and pos which will have biggest of N numbers or the biggest element of the array and position of that element in the array.

Explanation With Example

If int a[5] = {2, 4, 3, 4, 5};

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

        if(i == 0 || big < a[i])
        {
            big = a[i];
            pos = i + 1;
        }
    }

index	a[index]	big	pos = index + 1
0	a[0] = 2	2	1
1	a[1] = 4	4	2
2	a[2] = 3
3	a[3] = 4
4	a[4] = 5	5	5
5

a[5] = {2, 4, 3, 4, 5}
big = 5;
pos = 5;

Source Code: C Program To Find Biggest Element of An Array

Method 2

#include<stdio.h>

#define N 5

int main()
{
    int a[N], i, big, pos;

    printf("Enter %d integer numbers\n", N);
    for(i = 0; i < N; i++)
    {
        scanf("%d", &a[i]);
    }

    big = a[0];
    pos = 1;

    for(i = 1; i < N; i++)
    {
        if(big < a[i])
        {
            big = a[i];
            pos = i + 1;
        }
    }

    printf("\nBiggest of %d numbers is %d, at position %d.\n", N, big, pos);

    return 0;
}

Output 1:
Enter 5 integer numbers
1
5
6
3
0

Biggest of 5 numbers is 6, at position 3.

Output 2:
Enter 5 integer numbers
2
4
3
4
5

Biggest of 5 numbers is 5, at position 5

Method 2: LOGIC

Here we accept N integer numbers from the user. Next we assign the first element of the array to big and 1 to pos. Now we use another for loop to loop through the array. Inside for loop we check if the value present inside variable big is less than the value present at a[i]. If it’s true, then we assign the value of a[i] to big and value of (i+1) to variable pos.

At the end of for loop, variable big and pos will have biggest element of the array and the position at which this number is present in the array.

Note: Since we assign the value of first element of the array(which is present at location a[0]) to variable big, while comparing with other elements of the array, we start comparing from a[1] till a[N-1]. That’s the reason we’ve assigned initial value of i to 1 in the second for loop.

Since a[0] is assigned to variable big, there is no point in comparing big with a[0]. So we start comparison from a[1].

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

Using Macros Check For Uppercase / Lowercase and Alphabet or Not and Biggest of 2 Numbers: C Program

Problem State: Write down macro definitions for the following:
1. To test whether a character is a small case letter or not.
2. To test whether a character is an upper case letter or not.
3. To test whether a character is an alphabet or not. Make use of the macros you defined in 1 and 2 above.
4. To obtain the bigger of two numbers.

Problem Statement Analysis

1. We need to write 4 Macro definitions.
2. We must write macros to find upper and lower case, and then make use of these two macros to find if user entered character is alphabet or not.
3. We can find biggest of 2 numbers by using Ternary / conditional operator in macro expansion.

Video Tutorial: Using Macros Check For Uppercase / Lowercase and Alphabet or Not and Biggest of 2 Numbers: C Program

[youtube https://www.youtube.com/watch?v=EEGLYe2buxk]

YouTube Link: https://www.youtube.com/watch?v=EEGLYe2buxk [Watch the Video In Full Screen.]

Source Code: Using Macros Check For Uppercase / Lowercase and Alphabet or Not and Biggest of 2 Numbers: C Program

#include<stdio.h>

#define isUPPER(ch) ( ch >= 'A' && ch <= 'Z' )
#define isLOWER(ch) ( ch >= 'a' && ch <= 'z' )
#define isALPHABET(ch) ( isUPPER(ch) || isLOWER(ch) )
#define BIGGEST(a, b) ( ( a > b ) ? \
                       printf("%d is the biggest\n", a) : \
                       printf("%d is the biggest\n", b) )

int main()
{
    int a, b, repeat;
    char ch, choice;

    do
    {
        printf("1. Check if entered character is upper or lower case\n");
        printf("2. Check if entered character is alphabet or not\n");
        printf("3. Find biggest of 2 numbers\n");

        printf("\nEnter your choice\n");
        scanf(" %c", &choice);

        switch(choice)
        {
            case '1': printf("\nEnter a character\n");
                      scanf(" %c", &ch);

                      if( isUPPER(ch) )
                      {
                          printf("Entered character is upper case letter\n");
                      }
                      else if( isLOWER(ch) )
                      {
                          printf("Entered character is lower case letter\n");
                      }
                      else
                      {
                          printf("Please enter a valid alphabet\n");
                      }

                      break;
            case '2': printf("\nEnter a character\n");
                      scanf(" %c", &ch);

                      if( isALPHABET(ch) )
                      {
                          printf("Entered character is an alphabet\n");
                      }
                      else
                      {
                          printf("Entered character is not an alphabet\n");
                      }
                      break;
            case '3': printf("\nEnter 2 numbers\n");
                      scanf("%d%d", &a, &b);

                      BIGGEST(a, b);

                      break;
            default:  printf("\nPlease enter valid choice\n");
        }

        printf("\n\nDo you want to continue? Ans: 0 or 1\n");
        scanf("%d", &repeat);

        printf("\n");
        fflush(stdin);

    }while(repeat);

    return 0;
}

Output:
1. Check if entered character is upper or lower case
2. Check if entered character is alphabet or not
3. Find biggest of 2 numbers

Enter your choice
1

Enter a character
S
Entered character is upper case letter

Do you want to continue? Ans: 0 or 1
1