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Articles by Nishtha Thakur
Page 13 of 40
Update multiple rows in a single MongoDB query?
Use the concept of initializeUnorderedBulkOp(). Let us first create a collection with documents −>db.upDateMultipleRowsDemo.insertOne({"CustomerName":"John", "CustomerPurchaseAmount":500}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ceb06d78f205348bc626") } >db.upDateMultipleRowsDemo.insertOne({"CustomerName":"Chris", "CustomerPurchaseAmount":700}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ceb26d78f205348bc627") } >db.upDateMultipleRowsDemo.insertOne({"CustomerName":"David", "CustomerPurchaseAmount":50}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ceb36d78f205348bc628") } >db.upDateMultipleRowsDemo.insertOne({"CustomerName":"Larry", "CustomerPurchaseAmount":1900}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ceb46d78f205348bc629") }Following is the query to display all documents from a collection with the help of find() method −> db.upDateMultipleRowsDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd6ceb06d78f205348bc626"), "CustomerName" : "John", "CustomerPurchaseAmount" : 500 } { ...
Read MoreHow to detect a new Android notification?
This example demonstrate about How to detect a new Android notificationStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to src/MyListener.javapublic interface MyListener { void setValue (String packageName) ; }Step 3 − Add the following code to src/MyListener.javapackage app.tutorialspoint.com.notifyme ; import android.content.Context ; import android.service.notification.NotificationListenerService ; import android.service.notification.StatusBarNotification ; import android.util.Log ; public class NotificationService extends NotificationListenerService { private String TAG = this .getClass().getSimpleName() ; Context context ; static MyListener myListener ; @Override ...
Read MorePointers, smart pointers and shared pointers in C++
PointersPointers are used to store the address of variable.SyntaxType *pointer;InitializationType *pointer; Pointer = variable name;Functionspointers are used to store address of variable.pointers can have a null value assigned.pointer can be referenced by pass by reference.a pointer has its own memory address and size on the stack.Example Live Demo#include using namespace std; int main() { // A normal integer variable int a = 7; // A pointer variable that holds address of a. int *p = &a; // Value stored is value of variable "a" cout
Read MoreConcatenate fields in MongoDB?
To concatenate fields, use the $concat operator. Let us first create a collection with documents −>db.concatenateFieldsDemo.insertOne({"StudentFirstName":"Adam", "StudentLastName":"Smith"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ebf46d78f205348bc62e") } >db.concatenateFieldsDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Doe"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ebfc6d78f205348bc62f") } >db.concatenateFieldsDemo.insertOne({"StudentFirstName":"David", "StudentLastName":"Miller"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ec376d78f205348bc630") } >db.concatenateFieldsDemo.insertOne({"StudentFirstName":"Sam", "StudentLastName":"Williams"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6ec436d78f205348bc631") }Following is the query to display all documents from a collection with the help of find() method −> db.concatenateFieldsDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd6ebf46d78f205348bc62e"), "StudentFirstName" : "Adam", "StudentLastName" : "Smith" } ...
Read MoreHow to find datatype of all the fields in MongoDB?
Use typeof to find datatype of all the fields −typeof db.yourCollectionName.findOne().yourFieldName;Let us first create a collection with documents −> db.findDataTypeDemo.insertOne({"ClientName":"Chris", "isMarried":false}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf2064dceb9a92e6aa1952") }Following is the query to display all documents from a collection with the help of find() method −> db.findDataTypeDemo.findOne();This will produce the following output −{ "_id" : ObjectId("5ccf2064dceb9a92e6aa1952"), "ClientName" : "Chris", "isMarried" : false }Following is the query to find datatype of a field in MongoDB −> typeof db.findDataTypeDemo.findOne().isMarried;This will produce the following output −BooleanHere is the query to get the data type of another field −> ...
Read Moregetopt() function in C to parse command line arguments
The getopt() is one of the built-in C function that are used for taking the command line options. The syntax of this function is like below −getopt(int argc, char *const argv[], const char *optstring)The opstring is a list of characters. Each of them representing a single character option.This function returns many values. These are like below −If the option takes a value, then that value will be pointed by optarg.It will return -1, when no more options to procesReturns ‘?’ to show that this is an unrecognized option, it stores it to optopt.Sometimes some options need some value, If the ...
Read MoreHow to find Segmentation Error in C & C++ ? (Using GDB)
The segmentation error is one of the runtime error, that is caused because of the memory access violation, like accessing invalid array index, pointing some restricted address etc. In this article, we will see how to detect this type of error using the GDB tool.Let us see the code and respective steps to locate the error.Example#include main() { int* ptr = NULL; *ptr = 1; //trying to access unknown memory location printf("%p", ptr); }Compile the code using ‘gcc –g program_name.c’, and run using ‘./a.out’Outputsoumyadeep@soumyadeep-VirtualBox:~/Cpp_progs$ ./a.out Segmentation fault (core dumped)The segmentation error occurred.Write ‘gdb ./a.out core’soumyadeep@soumyadeep-VirtualBox:~/Cpp_progs$ gdb ...
Read MoreHow to prepend string to entire column in MongoDB?
Prepend string to entire column in MongoDB using aggregate framework. Let us first create a collection with documents −> db.prependDemo.insertOne({"StudentFirstName":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf3bcedceb9a92e6aa1955") } > db.prependDemo.insertOne({"StudentFirstName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf3bd3dceb9a92e6aa1956") } > db.prependDemo.insertOne({"StudentFirstName":"Robert"}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf3bd8dceb9a92e6aa1957") }Following is the query to display all documents from a collection with the help of find() method −> db.prependDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ccf3bcedceb9a92e6aa1955"), "StudentFirstName" : "John" } { "_id" : ObjectId("5ccf3bd3dceb9a92e6aa1956"), "StudentFirstName" : "Chris" } { "_id" : ObjectId("5ccf3bd8dceb9a92e6aa1957"), ...
Read MoreRint(), rintf(), rintl() in C++
Here we will see three functions. These functions are Rint(), rintf() and the rintl(). These functions are used to convert floating point values into rounded format.The rint() FunctionThis function is used for rounding floating point value to integer. The syntax is like below. If the result is outside of return type, the domain error may occur. When the argument is 0 or infinity, then it will return unmodifiedfloat rint(float argument) double rint(double argument) long double rint(long double argument)Example#include #include using namespace std; main() { double a, b, x, y; x = 53.26; y = 53.86; ...
Read MoreDecrement only a single value in MongoDB?
Let us first create a collection with documents −>db.decrementingOperationDemo.insertOne({"ProductName":"Product-1", "ProductPrice":756}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7a8ae6d78f205348bc63c") } >db.decrementingOperationDemo.insertOne({"ProductName":"Product-2", "ProductPrice":890}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7a8b86d78f205348bc63d") } >db.decrementingOperationDemo.insertOne({"ProductName":"Product-3", "ProductPrice":994}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7a8c66d78f205348bc63e") } >db.decrementingOperationDemo.insertOne({"ProductName":"Product-4", "ProductPrice":1000}); { "acknowledged" : true, "insertedId" : ObjectId("5cd7a8d06d78f205348bc63f") }Following is the query to display all documents from a collection with the help of find() method −> db.decrementingOperationDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd7a8ae6d78f205348bc63c"), "ProductName" : "Product-1", "ProductPrice" : 756 } { "_id" : ObjectId("5cd7a8b86d78f205348bc63d"), "ProductName" ...
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