Learn Computer science with Free Lessons & Tips

File (Flat) Handling in Python

Types of files in python:

1: Text file: Stores data in the form of characters. Customarily used to store text/string data.

2: Binary file: Stores data in the form of bytes. It can be used to store text, images, audio and video.

Open() Function:

To open a file, we use the open() function. Here we need to mention 'filename' and 'mode' in which we want to open that file.

Syntax: File Handler = open("FileName", "Mode")

Mode: w (write), r(read), a(append) etc.

A file that is opened should be closed with the help of the close() function.

To write in a file, we use the write() function.

Example:

A simple Python program to open, write, read and close a file.

# Open a file in write mode

f = open("myFile.txt","w")

# Take input from user

str = input("Enter text: ")

f.write(str) # Write the string into file

f.close() # Close the file

# Again open the file in read mode

print("Now Reading that file....")

f = open("myFile.txt","r")

str = f.read() # Read from file

# Display the content on the screen

print(str)

f.close() # Close The file

Thank You!

Python is the most common coding language and is widely used. It is a favourite tool along being a flexible and open-sourced language. Its massive libraries like- Numpy, Pandas, SciPy, Keras, Pytorch, Tensorflow, Scikit-Learn and e.t.c which are used for data manipulation and are very easy to learn for a beginner or for professionals who want to know.

Data Science is the broad field in which you can learn about many concepts like- Python and R programming, Statistics, Probability and other topics of Mathematics, Machine Learning Algorithms, Techniques, Data Visualization tools- Big Data, SQL, NoSQL, Apache-Spark, MongoDB, PowerBI and e.t.c.

To learn data science and their other concepts, I would suggest you CorpWin technologies Programs. Corwin is one of the best training platforms to learn data science in depth. They provide the best course curriculum in which you will get all essential concepts of data science like- Python and its massive libraries concepts, Mathematics concepts, Techniques of ML and e.t.c. 

Have you ever wondered, why did you learn so many subjects and what is the use of them, do you need to know them, will you be using them?

Well, my answer is the subjects that you study, covers different aspects of Computer Science. Computer Science is not only coding, after all.

For example, you work in an IT Company which provides solutions to some FMCG company. Now:
1. They need to have their computer network, need to manage the network.
2. They have a lot of data, which needs to be stored in the database. So effective database management is critical.
3. The company also need to have different kinds of applications, starting from their desktop app, website, mobile app. For developing these apps, knowledge of Algorithm and programming is extremely important.
4. For a standard and effective development process, following Software Engineering principles are fundamental.

5. We also need to learn about effective cost management.

6. Now if you work in an innovative product based company, then you need to work with Algorithms, Compilers, Theory of Computation, Operating Systems and perhaps some Maths as well.

7. There are many organizations which work on different hardware and networking devices. If you want to be a part of them, you need to know the related subjects as well.

This way, all the subjects we learn, have the potential to play a significant role in different phases of our career and for choosing different career options, where you can grow better and become successful.

Remember, learning doesn't harm; it can only benefit you, in the short term as well as in the long run.

Many students have difficulty in understanding pointers. The best way to understand pointers is through memory representation.

Whenever we declare a variable, the computer allocates some amount of memory corresponding to this particular variable. Pointers are variables that store the address of another variable

2Phase Lock in Distributed Database:

In this protocol, it is required that all the data items must be reached in a mutually independent manner, i.e. when one transaction is performing, then no other transaction should interrupt the process.

It requires both locks and unlocks being done in two phases:

• Growing Phase: Obtain locks that means when we are writing something on A and B, then we will take locks on A and B like below: W(A) and W(B)
• Shrinking Phase: Release locks, Unlock the objects in a row like unlock (A) and unlock (B)

But 2 PL won’t be able to solve other problems such as cascading rollback.

1. when we execute the java file, JVM is loaded into memory.
2. In JVM, first class loader starts which loads the class into memory, i.e. it divides the code intoRuntime Memory Area.
3. Runtime memory consists of:-

• a) Heap- All the objects in the program are stored in a heap.
• b) Stack- all the local and ref variables are in the stack.
• c) Method area- it is a permanent area. It consists of static variables, class definitions and fxns.
• d) Native code area- the code which is not a part of Java but is a part of the platform, ie., the operating system that's called native code
• e) Program counter register- holds the address of next instruction going to be executed.

4. After the class loader, execution engine (JIT) runs which translate bytecode to machine-operable code.

The software is the virtual component of the computer through which we are doing our work.

The software is classified as System software and Application Software.

System Software provides the platform for loading application software. System software is the one who controls the hardware and helps users to do their work. It is the soul of the computer system. Once the device is designed, system software is loaded to make it live.

It is similar to humans, where once the body (hardware) is built, the body attains its system software in the name of soul.

Without system software, the hardware is a dead body. And also without hardware, the software is useless.

Application software is a set of programs or commands written to do a user-specific task. Different people use different types of application software. Based on the user requirements, we load our application software on the primary system software. It is like the development of our mind and knowledge based on the situation, schooling, surroundings for a human being.

So generally hardware is the body of the computer, while system software and application software are considered as soul and mind of computer respectively.

In a computer, there are two major parts available namely hardware and software. both plays an important role in proper functioning of the computer. 

Hardware are the touchable and physical parts of the computer. Hardware are visible to the user and it is visible even to a blind man. It is like the body of computer. Hardware provides the basic skeleton to load and work with software.

Software are nothing but the imaginary parts or virtual parts of the computer. Software is more complex and unable to understand easily. It is like mind or soul of the computer. It can't be touched or damaged. After finishing the design of hardware, Software is loaded into it.

When the hardware and software are working together, it becomes a computer. Without software, computer hardware is just a electronic board with connections. Without hardware, software cannot be used and can be stored only in CD or Pen Drive.

Algorithm:

1) Create a stack to store operands (or values).

2) Scan the given expression and do following for every scanned element.

a) If the element is a number, push it into the stack.

b) If the element is a operator, pop operands for the operator from stack. Evaluate the operator and push the result back to the stack

3) When the expression is ended, the number in the stack is the final answer.

In many of the IT and Computer science formal courses, I have observed many of the topics are taught as independent unrelated threads. In order to get a deeper insight of the computer science, it is very much essential to understand how these thinking machines work and how the wisdom of many great minds have made it possible.

It is necessary to understand how such a complex machine is designed with a goal that something called software can make it do fascinating stuff. And in general, a computer system is not very much different than a human mind. Our mind stores the information what it receives via sensor organs like eye, ear, skin, tongue which are converted into electrical signals and a huge number of neuron present in brain process the information and finally take some action. Note that the language plays a very important role in the process as we think in our language and communicate with each other using a common language.

In the same way, a computer system also has something equivalent to human mind which is known as a microprocessor and which has its own language in which it thinks and takes actions. Again important thing to note is that the unlike mind it does not decide what to do but it knows if someone has given a set of instructions or command to it along with data then it can execute those commands or instructions on the given dataset and generate the desired results. These instructions can be entered to the microprocessor using its sensors like keyboard, mouse etc and it has just like human brain storage devices to keep information in persistent storage like hard disks, USB devices, SSD etc.

From above it can be related that the instructions given to microprocessor(think Intel x86, AMD) are in the language of the microprocessor and they are known as instruction set of that microprocessor. The simple instructions are like add, subtract, multiply, divide, load, store, move etc but these are only a fraction of the whole set and can be downloaded from the web to understand it at a deeper level. These instructions are nothing but series of bytes(8-bit) and the different bit patterns indicate the role of the instruction which microprocessor understand and then accordingly perform the given tasks, for example, add two numbers.

The software at a very high level is nothing but a collection of these instructions and the order of these instructions is the program logic which a programmer writes using high-level languages like C++, Java, C etc. The instructions are specific to a particular microprocessor and cannot be understood by other microprocessors.

The other interpretation of the above sentence is that any software written in any programming language is finally converted to the sequence of instructions for that processor where it is about to be run. This conversion of a high-level language program to the instruction set of target microprocessor is done by another software called "compiler". The task of the compiler is to first understand the program written in high-level programming language and convert it into the language of the machine i.e. machine instructions. These machine instructions are also provided in a human-readable form known as "Assembly Language". Assembly language is nothing but the sequence of human-readable English characters like add, sub, multiply etc and either compiler or another program known as assembler can convert these English characters to binary bytes or machine instructions. And finally, these binary interactions are given to microprocessor to execute the program logic. Always note that finally on the processor it is always the machine instructions which are binary eg. 11001010 and other than that it does not understand anything.

My next posts will start going deep on how microprocessor work and how it communicates with surroundings like RAM, HDD. Then we will go over the operating system, virtual memory etc in order to understand how a complete system finally work as we operate it using GUI based display units.