Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
Articles by Anvi Jain
Page 36 of 43
Printing 1 to 1000 without loop or conditionals in C/C++
Here we will see how to print 1 to 1000 without loop or any conditional statements. As the loops cannot be used, so we can try recursions, but here another constraint that, we cannot use the conditions also. So the base case of the recursion will not be used.Here we are solving this problem using static members. At first we are initializing the static member with 1, then in the constructor we are printing the value and increase its value. Now create an array of 1000 objects of that class, so 1000 different objects are created, so the constructor is ...
Read MoreFind value in a MongoDB Array with multiple criteria?
To find value in the array with multiple criteria, for example, you can use $elemMatch along with $gt and $lt. The syntax is as follows −db.yourCollectionName.find({yourFieldName:{$elemMatch:{$gt:yourNegativeValue, $lt:yourPo sitiveValue}}}).pretty();To understand the above syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.findValueInArrayWithMultipleCriteriaDemo.insertOne({"StudentName":"Larry", "StudentMarks":[-150, 150]}); { "acknowledged" : true, "insertedId" : ObjectId("5c77daf6fc4e719b197a12f5") } > db.findValueInArrayWithMultipleCriteriaDemo.insertOne({"StudentName":"Mike", "StudentMarks":[19]}); { "acknowledged" : true, "insertedId" : ObjectId("5c77db09fc4e719b197a12f6") }Display all documents from a collection with the help of find() method. The query is as follows −> db.findValueInArrayWithMultipleCriteriaDemo.find().pretty();The following is the ...
Read MoreWhat is a reentrant function in C/C++?
Here we will see what is the reentrant function in C or C++. One function is said to be a reentrant function if there is a provision to interrupt that function in the course of execution, then service the ISR (Interrupt Service Routine) and then resume the task. This type of functions is used in different cases like, recursions, hardware interrupt handling.For a reentrant function there should be some properties. These are listed below −This type of function will not use any global or static variable. There are no restrictions, but it is generally not advised. This is because the ...
Read MoreCollectors.joining() method in Java 8
The joining() method of the Collectors class in Java 8 returns a Collector that concatenates the input elements into a String, in encounter order.The syntax is as follows −public static Collector joining()Here, CharSequence is a readable sequence of char values, whereas String class represents character strings.To work with Collectors class in Java, import the following package −import java.util.stream.Collectors;The following is an example to implement Collectors.joining() method in Java 8 −Example Live Demoimport java.util.stream.Collectors; import java.util.stream.Stream; import java.util.Arrays; import java.util.List; public class Demo { public static void main(String[] args) { List list ...
Read MoreMultiline macros in C
In this section we will see, how can write multiline macros in C. We can write multiline macros like functions, but for macros, each line must be terminated with backslash ‘\’ character. If we use curly braces ‘{}’ and the macros is ended with ‘}’, then it may generate some error. So we can enclose the entire thing into parenthesis.Please check the following program to get the idea about multiline macros.Example#include #define PRINT(x, str) ({\ printf("The number %d", x);\ printf(" is ");\ printf(#str);\ printf("");\ }) int main() { int x = 10; if(x % 2 == 0){ PRINT(x, EVEN); } }OutputThe number 10 is EVEN
Read MoreSelect MongoDB documents where a field either does not exist, is null, or is false?
You can use $in operator for this. Let us first create a collection with a document. The query to create a collection with a document is as follows −> db.selectMongoDBDocumentsWithSomeCondition.insertOne({"StudentId":1, "StudentName":"Larry"}); { "acknowledged" : true, "insertedId" : ObjectId("5c9010215705caea966c557f") } > db.selectMongoDBDocumentsWithSomeCondition.insertOne({"StudentId":2, "StudentName":"Mike", "hasAgeGreaterThanOrEqualTo18":true}); { "acknowledged" : true, "insertedId" : ObjectId("5c90106a5705caea966c5580") } > db.selectMongoDBDocumentsWithSomeCondition.insertOne({"StudentId":3, "StudentName":"Carol", "hasAgeGreaterThanOrEqualTo18":false}); { "acknowledged" : true, "insertedId" : ObjectId("5c9010795705caea966c5581") } > db.selectMongoDBDocumentsWithSomeCondition.insertOne({"StudentId":4, "StudentName":"Sam", "hasAgeGreaterThanOrEqualTo18":null}); { "acknowledged" : true, "insertedId" : ObjectId("5c9010865705caea966c5582") } > db.selectMongoDBDocumentsWithSomeCondition.insertOne({"StudentId":5, "StudentName":"David", "hasAgeGreaterThanOrEqualTo18":false}); { "acknowledged" : true, "insertedId" : ObjectId("5c9010945705caea966c5583") } > db.selectMongoDBDocumentsWithSomeCondition.insertOne({"StudentId":6, "StudentName":"Chris", ...
Read MoreHow does free() know the size of memory to be deallocated?
The free() function is used to deallocate memory while it is allocated using malloc(), calloc() and realloc(). The syntax of the free is simple. We simply use free with the pointer. Then it can clean up the memory.free(ptr);The free() is not taking any size as parameter, but only pointer. So the question comes, that how the free() function know about the size of the block to deallocate?When we use the dynamic memory allocation techniques for memory allocations, then this is done in the actual heap section. It creates one word larger than the requested size. This extra word is used ...
Read MoreInsert records in MongoDB collection if it does not exist?
You can use update() function to insert records in MongoDB if it does not exist. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.insertIfNotExistsDemo.insertOne({"StudentName":"Mike", "StudentAge":21}); { "acknowledged" : true, "insertedId" : ObjectId("5c7eec7b559dd2396bcfbfc2") } > db.insertIfNotExistsDemo.insertOne({"StudentName":"Sam", "StudentAge":22}); { "acknowledged" : true, "insertedId" : ObjectId("5c7eec97559dd2396bcfbfc3") }Display all documents from a collection with the help of find() method. The query is as follows −> db.insertIfNotExistsDemo.find().pretty(); The following is the output: { "_id" : ObjectId("5c7eec7b559dd2396bcfbfc2"), "StudentName" : "Mike", "StudentAge" : ...
Read MoreHow to modify a const variable in C?
In C or C++, we can use the constant variables. The constant variable values cannot be changed after its initialization. In this section we will see how to change the value of some constant variables.If we want to change the value of constant variable, it will generate compile time error. Please check the following code to get the better idea.Example#include main() { const int x = 10; //define constant int printf("x = %d", x); x = 15; //trying to update constant value printf("x = %d", x); }Output[Error] assignment of read-only variable 'x'So this is generating ...
Read MoreHow are variables scoped in C
Here we will see how the C variables are scoped. The variables are always statically scoped in C. Binding of a variable, can be determined by the program text. These are independent of runtime function call stack.Let us see one example to get the idea.Example# include int x = 0; int my_function() { return x; } int my_function2() { int x = 1; return my_function(); } int main(){ printf("The value is: %d", my_function2()); }OutputThe value is: 0Here the result is 0. Because the value returned by my_function() is not depends on the function, which is ...
Read More