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Introduction to Rust string

The string is a data type in Rust that can be classified into two types, namely string literal written as &str, also known as string slice, and String object written as String, and the representation of &str is done by &[u8] that points to the UTP 8 sequence, and the data present in the string can be viewed using &str. The size of &str is fixed, meaning it cannot be resized. In contrast, the String object is encoded in UTF-8 sequence, and it is stored in heap memory with dynamic memory allocation. In contrast to a string literal, a String object in Rust has a dynamically changing size as it grows, and it is not terminated by a null character.

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The syntax to declare string literal or &str in Rust is as follows:

let variable_name:&str="string_to_be_stored";

In the given program, the term “variable_name” represents the actual name of the variable that stores the string.

string_to_be_stored is the string literal that will be stored inside the variable.

The syntax to declare a String object or String in Rust is as follows:

String::new()

We can create an empty string using the above syntax.

String::from()

We create a string with a default value by passing the default value as a parameter to the from() method.

Working of String in Rust

We use string literals or &str when the value of the string is known at compile time.

We call a set of characters hardcoded into a variable a string literal.

The module std::str consists of string literals.

The string literals are static in nature by default; that is, they are valid as long as the program is running.

The Standard library consists of the String object type.

The standard library pub struct string defines the String object type.

The size of the String object type is growable and can be resized.

The String object type is mutable.

The String object type in Rust encodes strings in UTF-8 sequence.

To represent string values at runtime, we can use the String object.

In Rust, the String object stores its data on the heap.

Examples of Rust string

Here are the following examples mentioned below

Example #1

Here is an example of a Rust program that demonstrates the use of string literals. It creates two string literals, stores values inside them, and then displays the output on the screen.

fn main() { let firststring:&str="Welcome to"; let secondstring:&str = "EDUCBA"; println!("The string stored using string literal is : {} {}",firststring,secondstring); }

In the given program, we use a string literal named “firststring” to store a specific string value. Then we create another string literal called secondstring to store another string value.

Then we display the two string values stored in the two string literals as the output on the screen.

Example #2

Here is an example of a Rust program that demonstrates the use of string objects. It creates an empty string using the new() method and another string object using the from() method. We pass the string that needs to be stored in the second string object as a parameter to the from() method. Finally, it displays the lengths of the two strings as the output on the screen using the len() method.

fn main() { let firststring = String::new(); let secondstring = String::from("EDUCBA"); println!("The length of the string stored in the firststring is : {} ",firststring.len()); println!("The length of the string stored in the secondstring is : {} ",secondstring.len()); }

The output of the above program is as shown in the snapshot below:

In the above program, we create an empty string called the firststring using the new() method. Hence we are creating another string called secondstring using the () method. To store the value of the string in the variable “secondstring,” we pass it as a parameter to the from() method. Then we use the len() function to find the length of each string. The program will output the lengths of the strings “firststring” and “secondstring” on the screen.

Example #3

Here is an example of a Rust program that demonstrates the use of String objects. The program creates two string objects by using the from() method and passing the strings as parameters to store them. Finally, it displays the length of the two strings using the len() method, and prints the output on the screen.

fn main() { let firststring = String::from("Welcome to"); let secondstring = String::from("EDUCBA"); println!("The length of the string stored in the firststring is : {} ",firststring.len()); println!("The length of the string stored in the secondstring is : {} ",secondstring.len()); }

The output of the above program is as shown in the snapshot below:

In the given program, we create two string objects, “firststring” and “secondstring,” using the from() method. To store the values of the strings in the variables “firststring” and “secondstring,” we pass them as parameters to the from() method. Then we use the len() function to find the length of each string. The program will display the length of the first string and the length of the second string as the output on the screen.

Conclusion

In this article, we have learned the concept of String literal and String Object in Rust through definition, syntax, and working String literal and String Object in Rust with corresponding programming examples and their outputs to demonstrate them.

How To Convert String Into Float In Javascript?

We can convert a string into a float using the parseFloat() function or the Number() constructor in JavaScript. Other approaches such as using + operator, eval() and parseInt() methods, can also be used for this. Converting strings to floating point numbers is a typical operation in JavaScript. This is required when working with numbers represented as strings, for as when reading data from an input field or a CSV file. In this article, we will learn these methods in detail.

Conversion Methods

There are several ways to convert a string into a float in JavaScript. The most common methods are the parseFloat() function and the Number() constructor.

The parseFloat() function

The parseFloat function is a tool in JavaScript that helps turn a string into a number with decimals. You give it a word or sentence, and it gives back a number. It’s easy to use and is built into JavaScript.

Syntax

The syntax of the parseFloat() function is as follows −

parseFloat(string) Example

Here is an example of how to use the parseFloat() function −

let string = “3.14”; let float = parseFloat(string); document.getElementById(“demo”).innerHTML = float;

Although the parseFloat() function is handy for converting a string to a float, it has several restrictions. Only the first part of the string that is a valid float is converted by the function. If there are any non-numeric characters after the float in the string, the function will ignore them.

The Number() Constructor

JavaScript includes a built-in function called Number() that offers an alternate way to turn a number represented as a string into a floating-point number. It returns the equivalent floating-point representation for a string that is sent in as an input. The Number() function offers a more flexible way for turning strings into floating-point numbers than the parseFloat() function does, and it can handle type conversions for a wider variety of data types, including integers and other numeric kinds.

Syntax

The syntax of the Number() constructor is as follows −

new Number(string) Example

Here is an example of how to use the Number() constructor −

let string = “3.114”; let float = new Number(string); document.getElementById(“demo”).innerHTML = float;

Although the Number() function is useful for converting a string to a float, it has several restrictions. The function is less performant than the parseFloat() function and should not be used.

Other Methods

There are also other methods for converting a string into a float in JavaScript. These methods include using the + operator, the parseInt() function and the eval() function.

The + operator

The + operator is a simple tool that helps you change a word into a number using float as input. Just give it a word that represents a number, and it will turn it into a type of number called a float. This tool is useful, but it only works with words that are actually numbers. It cannot change words that don’t represent numbers.

Syntax

The syntax of the + operator is as follows −

+string Example

Here is an example of how to use the + operator −

let string = “3.4”; let float = +string; document.getElementById(“demo”).innerHTML = float; The parseInt() Function

The parseInt() built-in JavaScript function converts a text to an integer or whole number. The parseInt() method accepts a string as input and outputs an integer value. To convert a string to a floating-point number, use the ParseInt() function and pass a radix (base) of 10 as an additional argument. Let’s look at an example to help us understand.

Syntax

The syntax of the parseInt() function is as follows −

parseInt(string, radix) Example

Here is an example of how to use the parseInt() function to convert a string into a float −

let string = “3.4”; let float = parseInt(string, 10); document.getElementById(“demo”).innerHTML = float; The eval() Function

The eval() method is a JavaScript built-in function that evaluates a string as a JavaScript expression. It accepts a string as an argument and returns a result, just like the parseInt() function. Converting a text to a float is a common use case for eval(). You can accomplish this by passing a string representing a float as an argument to eval (). After that, the function will evaluate the expression and return the float value. Overall, eval() is a useful function for running dynamic code, but it should be used with caution to avoid security concerns.

Syntax

The syntax of the eval() function is as follows −

eval(string) Example

Here is an example of how to use the eval() function to convert a string into a float −

let string = “3.456”; let float = eval(string); document.getElementById(“demo”).innerHTML = float;

Please take a note here that the eval() function is considered to be a dangerous function as it can execute any JavaScript code passed to it, which can be a cause of security risk if used improperly. Therefore, it is not recommended to use the eval() function to convert a string into a float.

Conclusion

How Do I Input A String From The User In Python?

In Python, there are several ways to input a string from the user. The most common method is by using the built-in function input(). This function allows the user to enter a string, which is then stored as a variable for use in the program.

Example

Here’s an example of how to input a string from the user in Python −

# Define a variable to store the input name = input("Please enter your name: ") # Print the input print("Hello, " + name + "! Good to see you.")

Output

The above code generates the following output for us −

Please enter your name: Max Hello, Max! Good to see you.

In the code above, we have,

Define a variable to store the input − name = input(“Please enter your name: “)

In this step, a variable named “name” is created to store the input from the user.

Prompt the user to enter their name − input(“Please enter your name: “)

The “input()” function is used to display a message to the user, asking them to enter their name. The message, “Please enter your name: “, is passed as an argument to the function.

Store the user’s input in the “name” variable − name = …

The result of the “input()” function call is stored in the “name” variable. This means that the user’s input is now stored in the “name” variable, ready to be used.

Print the input − print(“Hello, ” + name + “! Good to see you.”)

In this step, the “print()” function is used to display a message to the user, using the value stored in the “name” variable. The message, “Hello, [name]! Good to see you.”, is passed as an argument to the function. The value of “name” is concatenated with the rest of the string using the “+” operator.

It’s crucial to remember that the output of the “input()” function will always be a string, even if the user enters a numerical value. If you need to use the input as a number, you’ll need to convert it to the appropriate data type (e.g. int or float).

Example

Here’s an example of how to input a number from the user −

# Define a variable to store the input age = int(input("Please enter your age: ")) # Print the input print("Wow, you are " + str(age) + " years old!")

Output

The above code generates the following output for us −

Please enter your age: 24 Wow, you are 24 years old!

From the above code,

A variable named “age” is created to store the input from the user.

The message, “Please enter your age: “, is passed as an argument to the function.

Since the “input()” function always returns a string, we need to convert the user’s input to an integer using the “int()” function. This allows us to store the user’s input as a number, rather than a string.

The result of the “int()” function call is stored in the “age” variable.

The “print()” function is used to display a message to the user, using the value stored in the “age” variable. The message, “Wow, you are [age] years old!”, is passed as an argument to the function. The value of “age” is first converted to a string using the “str()” function and then concatenated with the rest of the string using the “+” operator.

It’s also possible to assign a default value to the input, in case the user doesn’t provide any input. This can be done using the “or” operator and a default value −

Example # Define a variable to store the input name = input("Please enter your name (or press enter for default): ") or "Max" # Print the input print("Hello, " + name + "! Good to see you.")

Output

The above code generates the following output for us −

Please enter your name (or press enter for default): Hello, Max! Good to see you.

Here in the code above,

A variable named “name” is created to store the name input by the user.

The message, “Please enter your name (or press enter for default) − “, is passed as an argument to the function.

The or operator is used to set a default value for the name variable. If the user presses enter without entering a name, the input() function will return an empty string. If the user’s input is an empty string, the or operator will evaluate to the default value, “Max”.

The result of the input() function call, or the default value “Max” is stored in the name variable.

A personalized greeting is printed, using the name variable. The + operator is used to concatenate the string values, creating a single string to be printed.

Conclusion

To summarize, receiving a string from a user in Python is a simple task that can be accomplished by making use of the readily available “input()” method. Regardless of whether you need to collect a string or a numerical value, it is effortless to convert the input into a suitable data type and save it in a variable for future reference.

The “input()” method is a convenient tool for obtaining information from a user and storing it for later use in your code.

Java Public Static Void Main(String Args)

The java programs start execution when JVM calls the main() method. Java application begin from this method. Without main method, a java file will compile successfully because at compile time, compiler doesn’t check for main method but at run time JVM checks whether the main() method is available or not. Therefore, we will get an exception at run time.

In this article, we will understand why we follow the convention “public static void main(String[] args).”

Syntax public class class_name { public static void main(String[] args) { } } Example 1 public class Tutorialspoint { public static void main(String []args) { System.out.println("Hello, you are on tutorials point"); } } Output Hello, you are on tutorials point

In our java file, at least one public class should be available. By convention, the main method must be defined within a class because everything comes inside a class in java. It shows that java is an object-oriented language.

In the above example, The class ‘Tutorialspoint’ contains main() method. Let’s discuss the parts of main() method −

public

Public is an access specifier that defines visibility or accessibility of a variable and method. The variables and methods defined using public keyword are accessible to any class and package. Earlier, we have discussed that JVM calls the main() method and it is not located in the current class. Therefore, main() method is declared as public so that we can access it globally or from anywhere.

What if we don’t use the public keyword along with main() method?

Example 2 public class Tutorialspoint { static void main(String []args){ System.out.println("Hello, you are on tutorials point"); } } Output Error: Main method not found in class Tutorialspoint, please define the main method as: public static void main(String[] args) or a JavaFX application class must extend javafx.application.Application

We are getting the error because JVM is unable to find main() method.

static

Generally, we call a method by creating an object of its class but static methods can be called without using objects. The JVM calls the main() method prior to the creation of any object that’s why we need to declare it as static.

Example 3

Most of the members of inbuilt class Math is static. We can use them directly without creating its object.

public class Main { public static void main( String[] args ) { double x = 6.55; double y = 4.32; System.out.println(" Ceil value of x: " + Math.ceil(x) ); System.out.println(" Floor value of y: " + Math.floor(y) ); } } Output Ceil value of x: 7.0 Floor value of y: 4.0

The above example illustrates the use of static methods ceil() and floor() of Math class. We can see that we have used them directly in our program without creating any object of Math class.

Let’s see what will happen if we don’t declare main() method as static.

Example 4 public class Tutorialspoint { public void main(String []args){ System.out.println("Hello, you are on tutorials point"); } } Output Error: Main method is not static in class Tutorialspoint, please define the main method as: public static void main(String[] args)

The JVM is not able to call the above code.

void

Let’s understand with an example −

Example 5 public class Tutorialspoint { public int main(String []args){ System.out.println("Hello, you are on tutorials point"); } } Output Tutorialspoint.java:4: error: missing return statement } ^ 1 error

It is a compile-time error. The compiler is asking for a return statement but it is of no use for JVM.

main()

main is the name of method don’t mistake it for a keyword. It is always written like ‘main’.

String[] args

String[] args is a parameter that accepts String type arguments. It allows us to pass arguments through terminal and it stores these arguments in an array of strings. We can say that String[] args is a command line argument.

Example 6

This example will illustrate how we can pass argument from terminal to a java file.

public class Arg { public static void main(String []args){ for(String arg : args) { System.out.println(arg); } } } Output

To compile the code from terminal type command: javac Arg.java

To run the code from terminal type command: java Arg “Your String”

Hello, You are on Tutorials Point

Conclusion

In this article, we have discussed the java programs to understand the use of “public static void main(String[] args).” We also discussed how we can take input from terminal using the parameter ‘String[] args.’

Why Is Rust Language Becoming Popular And Should You Learn It?

blog / Coding Why is Rust Language Becoming Popular and Should You Learn it?

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Even if you are not a coder, you may have heard of the more popular programming languages such as Java, C++, Python, or PHP. However, there is an addition to the list of favored programming languages among software developers. Rust programming language has gained recognition due to its ability to build high-performance applications. According to Statista, Rust was the 14th most-used programming language in the world in 2023. Let’s understand more about this programming language, its features, and its benefits.

What is the Rust Programming Language Used For?

Rust is a modern computer programming language developed by Mozilla in 2010. It was initially developed to build high-programming applications without the issue of invalid memory access that developers were facing while using C and C++. This system programming language facilitates designing and writing computer programs that allow smooth integration of computer hardware and software.

ALSO READ: Which Coding Language Should You Learn? Check This List Before You Start!

Why Should You Learn Rust Programming Language?

Rust facilitates easy scalability and concurrency and is suitable for building heavy applications to meet the increasing tech demands in the modern world.

It uses a logical and functional syntax that allows developers to handle low-level programming for IoT (Internet of Things) applications.

The old codes in Rust are compatible with the newer versions of the language.

Rust has an asynchronous processing model that allows developers to create and run independent functions, which can be collaborated later.

Features of Rust Programming Language

Safety and enhanced memory management without having a garbage collector (automatic memory management feature)

Zero-cost abstraction (a feature that allows developers to hide internal details of the code)

“Efficient C bindings” which allow developers to integrate Rust and C programming language features

A unique manual memory management feature that provides control of the allocation and deallocation of memory

A type interference feature that automatically determines an expression while coding

Advantages of Rust Programming Language

Reduces data compile time as it provides better concurrency than other programming languages

Provides low-level control for giving direct programming instructions, despite having a manual memory management feature

A friendlier syntax in comparison to C++ and provides better code safety

A relatively newer programming language and some of its features are not fully implemented

Does not support data structures like lists or vectors and is not object-oriented

Risk of memory leaks increased by the manual memory management feature in Rust

Example of Rust Programming Language

Here is an example of Rust code to help you understand Rust better and how it works:

First, you must create a chúng tôi file after installing Rust on Windows. Once you open the file, enter the below-given code:

fn main() {

println!(“Hello, world!”);

}

Now, you need to enter the following command on Windows

Hello, world!

After the command is complete, you will see “Hello, world!” printed on your screen.

How to Learn Rust Programming Language?

Rust is a high-level programming language with different features than C++ or Java. Therefore, you will need in-depth knowledge of programming to work on Rust. The following are some of the ways through which you can learn Rust and its best practices.

Reading Books

One of the best ways to learn the theoretical concepts of this language is to read books. Some of the most popular books on Rust are The Rust Programming Language (Covers Rust 2023), written by the Mozilla Team, and Beginning Rust Programming by Ric Messier.

Try Easy Codes

Once you gain sufficient knowledge of Rust, you should try easy coding exercises to learn the features of this language. Practicing various codes will help you learn the fundamental rules of Rust.

ALSO READ: Top 10 Inexpensive Ways to Learn How to Code

Install Programming Libraries

To make coding in Rust easier, you can install various programming libraries like Tokio, Bitflags, and Rand. You can use the pre-written codes available in these libraries to optimize your codes.

By Sneha Chugh

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Find Longest Palindrome Formed By Removing Or Shuffling Chars From String In C++

Concept

With respect of a given string, determine the longest palindrome that can be formed by removing or shuffling characters from the string. Finally return only one palindrome if it hasbeen observed that there is multiple palindrome strings of longest length.

Input pqr Output p OR q OR r Input ppqqrr Output pqrrqp OR qprrpq OR rqppqr OR any other palindromic string of length 6. Input pqp Output pqp Method

Here, We can partition any palindromic string into three parts – beg, mid and end. With respectof palindromic string of odd length say 2n + 1, here ‘beg’ consists of first n characters of the string, ‘mid’ consists of only 1 character that means (n + 1)th character and ‘end’ consists of last n characters of the palindromic string. With respect of palindromic string of even length 2n, there will be always empty in ‘mid’. We already knowthat ‘end’ will be reverse of ‘beg’ with respect of order for string to be chúng tôi the concept is to implement above observation in our solution. Because shuffling of characters is permitted, there is no matter of order of characters in the input string. Now we first obtain frequency of each character in the input string. After that all characters having even occurrence (say 2n)in the input string will be part of the output string because we can easily set n characters in ‘beg’ string and the other n characters in the ‘end’ string (with the help of preserving the palindromic order). With respect of characters having odd occurrence (say 2n + 1), here, we fill ‘mid’ with one of all such characters and remaining 2n characters are partitioned in halves and added at starting and end.

Example

Live Demo

using namespace std; string findLongestPalindrome(string str1){ // Indicated to stores freq of characters in a string int count1[256] = { 0 }; // Determine freq of characters in the input string for (int i = 0; i < str1.size(); i++) count1[str1[i]]++; // Shows any palindromic string consisting of three parts // beg1 + mid1 + end1 string beg1 = "", mid1 = "", end1 = ""; //Here solution assumes only lowercase characters are // present in string. We can easily extend this // to consider any set of characters for (char ch1 = 'a'; ch1 <= 'z'; ch1++){ if (count1[ch1] & 1){ mid1 = ch1; count1[ch1--]--; } // Here if the current character freq is even else{ for (int i = 0; i < count1[ch1]/2 ; i++) beg1.push_back(ch1); } } // Here end will be reverse of beg end1 = beg1; reverse(end1.begin(), end1.end()); // Now return palindrome string return beg1 + mid1 + end1; } int main(){ string str1 = "pqqprrs"; cout << findLongestPalindrome(str1); return 0; } Output pqrsrqp

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