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Programming Scripts Articles
Page 24 of 33
The fork() Function in Perl
Perl provides a fork() function that corresponds to the Unix system call of the same name. On most Unix-like platforms where the fork() system call is available, Perl's fork() simply calls it. On some platforms such as Windows where the fork() system call is not available, Perl can be built to emulate fork() at the interpreter level.The fork() function is used to clone a current process. This call create a new process running the same program at the same point. It returns the child pid to the parent process, 0 to the child process, or under if the fork is ...
Read MoreWhat is the difference between #define and const Keyword in C++?
In C++, both #define and const are used to define constants in a program. The #define is a preprocessor directive that creates macros with their fixed values whereas const is a keyword which declare value of variable as constant, meaning its value cannot be changed after intialization. Therefore they have different use cases in different scenarios. In this article, we will learn the differences between these two in detail. #define in C++ The #define is a preprocessor directive that is used to define or assign macros ( name or string ) with a constant value. So wherever the macro occurs ...
Read MoreDifference Between & and && in C Programming
The "&" and "&&" operators are both logical AND operators in most programming languages, but they can behave differently in certain circumstances. Both "&" and "&&" are operators used for evaluating conditional statements. The most basic difference between the two is that the "&" operator is a logical as well as a bitwise operator, whereas the "&&" operator is only a logical operator. Read this article to find out more about these two operators and how they are different from each other. Let's start with a basic overview of "&" and "&&" operators. What is "&" Operator? The & operator ...
Read MoreHow to count the number of keys in a Perl hash?
There are times when we would want to know how many key-value pairs are present in a hash. These key-value pair counts are also known as the size of the hash. In Perl, we can find the number of keys in a Perl hash by using the "scalar" keyword or "keys" keyword. In this tutorial, we will explore two Perl examples where we will calculate the number of keys in a hash. Example Consider the code shown below. In this code, we have declared a hash named "countries" and in that hash, we have different countries, each having ...
Read MoreHow to count the number of matches in a Perl string?
In Perl, we can find the number of matches in a string by different approaches. In this tutorial, we will discuss the three most widely used approaches. Searching for a Single Character in a Perl String Let's first take the case where we would want to search for a single character pattern in a string. For example, let's suppose we have a string that look something like this − "India.Japan.Russia.USA.China" And, we want to find the number of times "." (dot) appears in the above string. Example Consider the code shown below. my $countries ...
Read MoreHow to convert binary to decimal and vice versa in Perl?
The conversion between binary to decimal and decimal to binary is a necessity when it comes to dealing with binary data and using them in some simple applications. In Perl, we can convert from decimal to binary and vice versa in multiple ways. In this tutorial, we will explore different examples where we will first convert a decimal value into a binary value and then a binary value into a decimal value. Decimal to Binary in Perl Let's first see an example where we are given two decimal values and we want to convert them to their binary representation. ...
Read MoreHow to convert a string to a number in Perl?
In Perl, we can convert a string into a number by appending the integer value 0 in front of it. There are some other approaches too, which we will discuss in this tutorial with the help of examples. Example Let's first consider the case where the string that we are trying to convert looks something like "123abc" or "23Hzbc". You can see that the it is a mixture of both integer values and characters. Consider the code shown below. my $firstStr = '23ASDF'; print "Convering First String to Number: ", $firstStr + 0; print ""; my $secondStr = ...
Read MoreHow to compare two strings in Perl?
Perl has methods and operators that determine whether two string values are equal or different. In Perl, the compare strings function is essential for comparing two strings and their values. This check examines if two string values are equal or not by using the "eq" and "ne" operators. We can also compare two strings with the help of the "lt, gt, ge, le" operators as well. In this tutorial, we will consider all the approaches that can be used to compare two strings in Perl. The "eq" and "ne" Operators in Perl Let's start with the eq and ...
Read MoreHow to Use cd Command in Bash Scripts
The cd command is one of most fundamental commands in Bash shell. It is used to change current working directory to a specified location. This command is particularly useful when navigating through file system, especially in situations where you need to access files or directories in a different location. In this article, we will explore how to use cd command in Bash scripts. What is cd Command? Before diving into usage of cd command, it is important to understand what it does. cd command is a built-in command in Bash that is used to change current working directory. When you ...
Read MoreHow to check if a file exists in Perl?
In this tutorial, we will take a couple of examples and demonstrate how you can if a file exists or not, with the help of Perl. Let's suppose we have a simple text file called "sample.txt" with the following data − This is a sample txt file that contains some content inside it. TutorialsPoint is simply amazing! We will use a Perl code to check whether this file exists or not. Example 1 The most basic approach to check whether a file exists or not is to use the "-e" flag and then pass the name of the file. ...
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