Tag: operator

C Program To Find Biggest of 3 Numbers using Binary Minus Operator

Lets write a simple C program to find biggest of three numbers using binary minus operator.

Related Read:
if else statement in C
Nested if else Statement In C

Logic To Find Biggest of 3 Numbers using Binary Minus Operator

If user enters a = 1, b = 2, c = 3;

We check if a – b > 0 and a – c > 0
i.e., 1 – 2 > 0 and 1 – 3 > 0
=> -1 > 0 and -2 > 0 (Both these conditions are false).
So a is not the biggest.

In else block we check if b – c > 0
=> 2 – 3 > 0
=> -1 > 0 (which is false)
So b is not the biggest.

In that case whatever number present in variable c is biggest.

Video Tutorial: C Program To Find Biggest of 3 Numbers using Binary Minus Operator


[youtube https://www.youtube.com/watch?v=2kpHLoBdBjc]

YouTube Link: https://www.youtube.com/watch?v=2kpHLoBdBjc [Watch the Video In Full Screen.]

Source Code: C Program To Find Biggest of 3 Numbers using Binary Minus Operator

#include < stdio.h >

int main()
{
    int a, b, c;

    printf("Enter 3 numbers\n");
    scanf("%d%d%d", &a, &b, &c);

    if(a-b > 0 && a-c > 0)
    {
        printf("%d is the biggest\n", a);
    }
    else
    {
        if(b-c > 0)
        {
            printf("%d is the biggest\n", b);
        }
        else
        {
            printf("%d is the biggest\n", c);
        }
    }

    return 0;
}

Output 1:
Enter 3 numbers
1
2
3
3 is the biggest

Output 2:
Enter 3 numbers
10
30
20
30 is the biggest

Output 3:
Enter 3 numbers
100
50
75
100 is the biggest

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Equal to v/s Strictly Equal to

What’s the difference between equal to v/s strictly equal to and not equal to v/s strictly not equal to in any programming language?

This seems to be confusing at first, but if we execute a small example things get very clear about the working of these operators.

strictly-not-equal-to

== is called equal to operator.
!= is called not-equal to operator.
=== is called strictly equal to operator.
!== is called strictly not-equal to operator.

In this video tutorial we shall see the differences between == v/s === and != v/s !===

Difference between != v/s !=== and == v/s ===


[youtube https://www.youtube.com/watch?v=ql5cS8DntwQ]

YouTube Link: https://www.youtube.com/watch?v=ql5cS8DntwQ [Watch the Video In Full Screen.]



$a = 1;
$b = '1';

Lets assign integer 1 to variable a and string ‘1’ to variable b.

Equal-to v/s Strictly Equal-to

$a == $b
true
 
$a === $b
false

== operator doesn’t consider the type of variable strictly, thus returns true even though we are comparing a string with an integer. But === operator considers the type of the variable strictly and treats integer and string as two different things and hence returns false.

Not Equal-to v/s Strictly Not Equal-to

$a != $b
false
 
$a !== $b
true

Similarly, as != operator doesn’t take variable type into strict consideration it thinks $a and $b as equals, hence returns false, but !== returns true as it reads integer and string variables as different.

Working With Arrays: MongoDB

Lets learn some of the methods and operators to work with arrays in MongoDB.

In this video tutorial, we’ll be looking at:
update()
$set
$push
$pop
$pushAll
$pull
$pullAll
$addToSet

update set push pop pushAll pull pullAll addToSet operators mongodb

test database, names collection

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MongoDB shell version: 2.6.1
connecting to: test
> db.names.find()
 
> db.names.insert({"_id": 1, "a": [1, 2, 3, 4]});
WriteResult({ "nInserted" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 1, 2, 3, 4 ] }

We insert a document into “names” collection. We’ll be working on the array field present in the document.

Working With Arrays: MongoDB


[youtube https://www.youtube.com/watch?v=xc5TiSqvnPQ]

YouTube Link: https://www.youtube.com/watch?v=xc5TiSqvnPQ [Watch the Video In Full Screen.]



update() method

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> db.names.update({"_id": 1}, {"a": [1, 2, 3, 4, 5]});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 1, 2, 3, 4, 5 ] }

We can update the array by simply using update() method. But here, we need to remember all the elements of the array as well as the new element to be inserted into the array. Thus, this method is somewhat tedious.

$set operator

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> db.names.update({"_id": 1}, {$set: {"a.5": 6}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 1, 2, 3, 4, 5, 6 ] }

We could insert an element into the array by making use of $set operator. Here we need to know the position where the new element needs to be inserted. In mongoDB, array index starts from zero.

$push operator

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> db.names.update({"_id": 1}, {$push: {"a": 7}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 1, 2, 3, 4, 5, 6, 7 ] }

using $push operator we can insert an element to the right hand side of the array. Here we simply specify the key and the value/element to be inserted.

$pop: {a: 1}

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> db.names.update({"_id": 1}, {$pop: {"a": 1}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 1, 2, 3, 4, 5, 6 ] }

$pop operator which has 1 as value to the key, removes the right most element from the array.

$pop: {a: -1}

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> db.names.update({"_id": 1}, {$pop: {"a": -1}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 2, 3, 4, 5, 6 ] }

$pop operator which has -1 as value to the key, removes the left most element from the array.

$pushAll operator

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> db.names.update({"_id": 1}, {$pushAll: {"a": [7, 8]}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 2, 3, 4, 5, 6, 7, 8 ] }

$pushAll operator inserts all the elements(array of elements) specified, to the right hand side of the existing array.

$pull operator

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> db.names.update({"_id": 1}, {$pull: {"a": 3}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 2, 4, 5, 6, 7, 8 ] }

$pull operator pulls or removes the specified element from the array, irrespective of its position.

$pullAll operator

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> db.names.update({"_id": 1}, {$pullAll: {"a": [2, 7, 8]}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 4, 5, 6 ] }

$pullAll operator pulls/removes all the elements(array of elements) specified from the array, irrespective of its position.

$addToSet operator

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> db.names.update({"_id": 1}, {$addToSet: {"a": 3}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find()
{ "_id" : 1, "a" : [ 4, 5, 6, 3 ] }

$addToSet operator adds specified element to the array, if its not already present in the array. If the element is already present in the array, then it doesn’t add it once again.

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> db.names.update({"_id": 1}, {$addToSet: {"a": 3}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
> db.names.find()
{ "_id" : 1, "a" : [ 4, 5, 6, 3 ] }

If the element is already present in the array, then $addToSet doesn’t add it once again.

Increment($inc) operator: MongoDB

Lets learn how to use $inc operator with update() method in MongoDB.

inc operator with update

test database, names collection

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> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 1
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

Here we have 2 documents. And we’ll be working on first document to illustrate the working of $inc operator.

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> db.names.update({"Company": "Google"}, {$inc: {"No": 2}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 3
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

Here “No” field will be incremented by 2. So the final value of “No” field is 3 (1+2).

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> db.names.update({"Company": "Google"}, {$inc: {"Sl_no": 1}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 3,
        "Sl_no" : 1
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

If we apply $inc operator on an non-existing field, it will be created with the increment value itself.

Increment($inc) operator: MongoDB


[youtube https://www.youtube.com/watch?v=LjJJOY4DLMs]

YouTube Link: https://www.youtube.com/watch?v=LjJJOY4DLMs [Watch the Video In Full Screen.]



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> db.names.update({"Company": "Google"}, {$inc: {"No": 1}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 4,
        "Sl_no" : 1
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

Here we increment the value of “No” once again by 1. So the final value of “No” field is 4 (3+1).

Update with UNSET Operator: MongoDB

Lets use $unset operator along with update() method, to update the documents.

update with set operator mongodb Update with UNSET Operator: MongoDB

test database, names collection

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> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "Product" : "Nexus",
        "No" : 1
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

Here we have 2 documents with fields _id, Company, Product and No.

Update with UNSET Operator: MongoDB


[youtube https://www.youtube.com/watch?v=8UUdITiZ5ZE]

YouTube Link: https://www.youtube.com/watch?v=8UUdITiZ5ZE [Watch the Video In Full Screen.]



We could remove a field using update() method, by not specifying it in the second argument.

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> db.names.update({"No": 1}, {"Company": "Google", "No": 1});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 1
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

Related Read: Update Method: MongoDB

This way, we could eliminate the field Product. But this is a tedious process – we need to remember all the fields inorder to achieve this. It gets difficult when we have many fields in our document. To solve this problem, we have $unset operator, where we only need to know the field name which we want to remove.

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> db.names.update({"No": 1}, {$unset: {"Product": 1}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 1
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

$unset operator syntax is same to unset or remove array from a document.

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> db.names.update({"No": 1}, {$set: {"Product": ["LG", "Samsung", "HTC"]}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 1,
        "Product" : [
                "LG",
                "Samsung",
                "HTC"
        ]
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}
 
> db.names.update({"No": 1}, {$unset: {"Product": 1}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
 
> db.names.find().pretty()
{
        "_id" : ObjectId("53c3fc2005e0ce2719d91bd2"),
        "Company" : "Google",
        "No" : 1
}
{
        "_id" : ObjectId("53c3fd3bb9ae26fa217b1e12"),
        "Company" : "Apple",
        "Product" : "iPhone",
        "No" : 2
}

Related Read: Update with SET Operator: MongoDB