Correct answer: declaring the formal parameters constant
Concept note Declaring the formal parameters as a constant which then prohibits any change to the contents of the actual parameters. We can also declare the actual parameters constant, which in turn would require formed parameters to be constant but this is overly restrictive as this would not allow any modification in the coller function also.
Concept note In computer programming language, primitive data types are the basic data types that are built into a programming language. They are typically simple, indivisible values that cannot be broken down into smaller components. Primitive data type - Integer, Float, Boolean, char, byte,
double.
Non-primitive data type - Arrays, structures classes, strings, pointers.
Concept note Here's a breakdown to each steps - 1. string var1[ ]; declares an array of strings called var1. 2. var1 = new string [3]; initializes the var1 array with a length of 3. 3. Since the no value assigned to the array elements, they are initialized with their default values, which is null for strings in java. 4. System.out.println(var1[1]), attempts to print the value of the second element of the var1 array. Since the second element of the array is null, the output will be null.
Correct answer: two accompanying interfaces and one XML file
Concept note Every Enterprise Java Beans (EJB) class file has two accompanying interfaces and one XML file. Two interfaces -1 Remote interface - specifies the business methods that clients of the object can invoke. 2. Home interface - Defines EJB life cycle methods such as a method to create and retrieve a reference to the bean object. One XML file - The XML file contains the deployment descriptor, which declares the contents of the module, defines the structure and external dependencies of the beans in the module and describes how the beans are to be used at run time.
Concept note The implementation phase of the Software Development Life Cycle (SDLC) involves the following activities. 1. Program testing - Verifying that the software meets the requirements and works as expected. 2. File conversion - Converting existing from the old system to the new system. 3. User training - Educating users on how to use the new system on the other hand, New changes to the system is an activity that typically belongs to the maintenance phase, which occurs after the implementation phase. The maintenance phase involves making updates, fixes and changes to the system after it has been deployed.
Concept note Spiral model works as with the combination of interative development process model and linear development model. Which has a major level of risk analysis involved in the process.
Concept note According to the PUTNAM model, the project effort (E) is inversely proportional to the fourth power of the development time (T) expressed as-
1
∝
E
4
T
If the development schedule is doubled, then the effort can be calculated as -
4
T
=
×
1
E
E
2
1
T
2
Given that T2 = 2T1, We substitute,
4
1
1
=
×
=
×
E
E
E
2
1
1
2
16
If the initial effort E1 = 100 person - months the new effort becomes
1
=
×
=
E
100
6.25PM
2
16
Concept note In virtual memory paging, the page size and frame size are equal- In virtual memory paging, each page is stored in a frame of the main memory. The size of a frame is the same as the size of a page for example- if a page size is 4096 bytes, then each frame will also hold 4096 bytes.
Concept note In UNIX the command prompt can be changed by modifying the value of the PS1 variable. PS1 stands for primary prompt string and is used to specify the format of the command prompt. To change the command prompt you can use the
PS1 = "new - prompt - string".
Concept note The optimal page replacement algorithm requires knowledge of future page references to make the best decision about which page to replace. This algorithm chooses the page that will not be needed for the longest time in the future. The optimal algorithm is also known as the clairvoyant algorithm because it requires knowledge of future events to make decisions.
Concept note From the table below, we can see that pages have been transferred into frames 9 times.
A
B
C
D
A
B
E
A
B
C
D
E
A
A
A
D
D
D
E
E
E
B
B
B
A
A
A
C
C
C
C
C
B
B
B
D
According to the FIFO algorithm, the first page to enter is the first page that should be replaced. Every time a page is required by a process, and existing page needs to be replaced from the memory with the page that is needed.
Concept note fork ( ) - create a new child process which runs concurrently with the parent. Each call to fork ( )
doubles the number of processes. 1. printf (" 1") - This is executed only by the original process, so 1 is printed once. 2. fork ( ) - Two processes now exist, parent P1 and child C1. 3. printf ("2") - Both processes (P1 and C1) execute this, so 2 is printed twice. 4. fork ( ) - Each of the two processes (P1 and C1) creates a child process, resulting in 4 processes. P1, C1, child of P1 (C2) and child of C1(C3). 5. After the third fork ( ) - Each of the four processes forks again, creating 8 processes in total. 6. printf ("3") this statement is executed by all 8 processes, so 3 is printed 8 times.
Correct answer: an extension of indexed allocation
Concept note The Unix file system used an extension of indexed allocation. It uses direct blocks, single indirect blocks, double indirect blocks and triple indirect blocks. Indexed allocation is a file allocation method where a separate index block is used to store painters to the data blocks of a file.
Concept note If a function does not modify the database, the purity level is WNDS. It covered code does not insert, update, delete or otherwise change data in the database.
Concept note 2 phase locking (2PL) is a concurrency control method that guarantees serializability. The protocol utilizes locks applied by a transaction to data, which may block other transaction from accessing the same data during the transaction's life. 2PL may be lead to dead locks that result from the mutual blocking of two or move transactions.
Concept note In relational database management systems different classes of relations are created using normal forms to prevent modification anomalies. Normalization is the process of organizing data to reduce redundancy and improve data integrity.
Concept note An Entity relationship model uses a diagram called an ER diagram to represent the structure of a database. An ER model is a database architecture or blueprint that can be implemented as a database later.
Concept note Simple locking scheme 1. Shared lock (S) 2. An exclusive lock (X) Shared lock (S) - If transaction locked data item in shared mode, allowed to read - only. Exclusive lock (X) - If transaction locked data item in shared mode, allowed to read and write both. From the above table, we can see that if one transaction has a shared lock on a data item and if one other transaction request for a shared lock on the same data item it will be immediately granted.
Correct answer: data, data relationship, data semantics and consistency constraints
Concept note In conclusion, a data model is a collection of conceptual tools for describing data, data relationships, data semantics and consistency constraints. It is important in designing a database system that is efficient flexible and easy to maintain.
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