Check out the top 10 strange features in programming languages

Every programming language has its own "quirks", such as strange syntax, unique functions or non-standard implementation methods. Programmers also have their own habits, which will make many programmers, even some experienced developers, feel crazy when facing a new language. The features of these languages ​​sometimes become stumbling blocks for programmers, and sometimes programmers slowly understand these features and gradually adapt to and like them. While there are countless features of all languages, there are not so many that programmers always discuss. In this article, we have listed the top 10 strange features of programming languages ​​that drive programmers crazy the most.

1. '+' is a concatenation operator in JavaScript

Strange feature: In JavaScript, '+' is an overloaded operator, which is both a plus sign (+) between numbers and a string. Joiner. If in a '+' operation, one of the operands is a string, JavaScript will convert the other operand into a string. At this time, '+' is a concatenation operator, so the result of '1' + 1 is '11'.

Cause analysis: The root cause of this problem is that JavaScript is a weakly typed language. But like Python, although '+' is also a connection operator between strings, Python is a strongly typed language. When programmers want to add strings and integers together, the program will report an error.

2. A class in Perl must return TRUE

Strange feature: Classes in the Perl language often end with a return 1 statement, because if the last statement in the class does not return a TRUE value, a TRUE value will be generated. mistake.
Cause analysis: Classes in Perl can contain some initialization work and subroutines. When the file is loaded, Perl begins checking whether the program executed successfully by looking for a TRUE return value. Even if there is no initialization code part in the class, Perl expects the class to return a TRUE value at the end, otherwise an exception will be thrown.

3. Trigrams in C and C++

Strange feature: C and C++ support 9 trigrams, which will convert the trigram into a single character before subsequent processing, such as '??! ' will be converted to /, which will make the source code more difficult to read, and sometimes unexpected problems will occur.
Cause analysis: The three-character group was originally used to help early C programmers type some characters that were not available on the keyboard, such as curly braces.

4. Case insensitivity in PHP

Strange feature: Identifiers in many programming languages ​​are case sensitive, but in PHP function and class names, case insensitivity is not present. That's fine, but what confuses programmers the most is that PHP's variable names, constants, and class attributes are case-sensitive.
Cause analysis: Most likely, PHP is a programming language that has gradually developed from CGI scripts.

5. 0 in Ruby represents TURE

Strange feature: In Ruby, the value 0 represents TRUE, which is completely opposite to other languages ​​such as C and Python. In these languages ​​0 represents FALSE, which is also true. This confuses many developers who are new to Ruby.
Cause analysis: In Ruby, only bool values ​​FALSE and nil are equal to FALSE, all others are TRUE, and 0 is the same as other numbers.

6. Use spaces to separate “blocks” in Python

Strange feature: Neither punctuation nor keywords are used. Python uses unique indentation levels to determine which part a certain line of code belongs to. Having the wrong number of spaces or mixing spaces and tab keys can cause errors.
Cause analysis: This may be related to Python's efforts to produce more readable code and reduce typing, and many code editors now support automatic indentation.

7. Array subscripting in C language is like doing pointer arithmetic

Strange feature: In addition to treating i as the subscript in array a, expressed as a[i], C also allows Represent the same element as i[a].
Cause analysis: In C language, arrays are like pointers in memory, so a[i] = *(a+i) = *(i+a) = i[a].

8. Predefined variables in Perl

Strange feature: Perl has a long list of special variables, and they all have confusing names. For those who are not Perl experts, they often need to consult the Perl documentation to understand the meaning of these codes.
Cause analysis: These variables usually provide some information about program execution, such as process ID ($$), error message ($@), and regular expression matching ($^R).

9. JavaScript automatically inserts semicolons

Strange feature: JavaScript only considers using a semicolon as the end of a statement as an option because it automatically inserts a semicolon, such as after a newline character. But this usually produces an error when no exception is thrown.

Cause analysis: The semicolon is inserted for convenience, so that programmers, especially novice programmers, find JavaScript syntax very easy.

10. Type conversion involving Integer in Java

Strange feature: Java will automatically convert the original type into an object, such as converting the int type to an Integer object. The default value of the Integer object is from -128 to 127. This can cause problems when using '==' to compare two Integers with the same value (only returns TRUE if -128-127, otherwise returns FALSE).
Cause analysis: This conversion will reduce the amount of code for programmers and improve performance.