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The macro is unhygienic: it declares a new variable in the existing scope which remains after the loop. One foreach macro cannot be defined that works with different collection types (e.g., array and linked list) or that is extensible to user types. C string as a collection of char
Python supports a wide variety of string operations. Strings in Python are immutable, so a string operation such as a substitution of characters, that in other programming languages might alter the string in place, returns a new string in Python. Performance considerations sometimes push for using special techniques in programs that modify ...
In JavaScript, function objects have an apply method, the first argument is the value of the this keyword inside the function; the second is the list of arguments: func . apply ( null , args ); ES6 adds the spread operator func(...args) [ 3 ] which may be used instead of apply .
Python also provides methods, often called dunder methods (due to their names beginning and ending with double-underscores), to allow user-defined classes to modify how they are handled by native operations including length, comparison, in arithmetic operations and type conversion. [112]
In Python, a generator can be thought of as an iterator that contains a frozen stack frame. Whenever next() is called on the iterator, Python resumes the frozen frame, which executes normally until the next yield statement is reached. The generator's frame is then frozen again, and the yielded value is returned to the caller.
After scanning the variable arguments a first time with va_arg and the first va_list (disposing of it with va_end), the programmer could scan the variable arguments a second time with va_arg and the second va_list. va_end needs to also be called on the cloned va_list before the containing function returns.
However, once the eval function had been manually compiled it was then used as part of a simple read-eval-print loop which formed the basis of the first Lisp interpreter. Later versions of the Lisp eval function have also been implemented as compilers. The eval function in Lisp expects a
For function that manipulate strings, modern object-oriented languages, like C# and Java have immutable strings and return a copy (in newly allocated dynamic memory), while others, like C manipulate the original string unless the programmer copies data to a new string.