memory-address

问题 What does <function at 'somewhere'> mean? Example: >>> def main(): ... pass ... >>> main <function main at 0x7f95cf42f320> And maybe there is a way to somehow access it using 0x7f95cf42f320 ? 回答1: You are looking at the default representation of a function object. It provides you with a name and a unique id, which in CPython happens to be a memory address. You cannot access it using the address; the memory address is only used to help you distinguish between function objects. In other words,

问题 I am answering a textbook question from this textbook. I am learning about pointers in C and have come across l-values and r-values. From my understanding: l-values are values that are defined after they are executed (++x) r-values are values that are not defined after they are executed (x++) It that correct? The question I wanted to answer (with my attempts): a) Which of the following C expressions are L-Values? 1. x + 2 Not a L value 2. &x Is a L value 3. *&x Is a L value 4. &x + 2 Not a L

问题 How do I get the absolute address of a member function in C++? (I need this for thunking.) Member function pointers don't work because I can't convert them to absolute addresses ( void * ) -- I need to know the address of the actual function in memory, not simply the address relative to the type. 回答1: There exists a syntax to get the address of the member function in MSVC (starting from MSVC 2005 IMHO). But it's pretty tricky. Moreover, the obtained pointer is impossible to cast to other

问题 Given knowledge of the prototype of a function and its address in memory, is it possible to call this function from another process or some piece of code that knows nothing but the prototype and memory address? If possible, how can a returned type be handled back in the code? 回答1: On modern operating systems, each process has its own address space and addresses are only valid within a process. If you want to execute code in some other process, you either have to inject a shared library or

问题 My code is: #include <stdio.h> #include <string.h> void main() { char string[10]; int A = -73; unsigned int B = 31337; strcpy(string, "sample"); // printing with different formats printf("[A] Dec: %d, Hex: %x, Unsigned: %u\n", A,A,A); printf("[B] Dec: %d, Hex: %x, Unsigned: %u\n", B,B,B); printf("[field width on B] 3: '%3u', 10: '%10u', '%08u'\n", B,B,B); // Example of unary address operator (dereferencing) and a %x // format string printf("variable A is at address: %08x\n", &A); I am using

问题 Is it possible to find the memory address of a JavaScript variable? The JavaScript code is part of (embedded into) a normal application where JavaScript is used as a front end to C++ and does not run on the browser. The JavaScript implementation used is SpiderMonkey. 回答1: If it would be possible at all, it would be very dependent on the javascript engine. The more modern javascript engine compile their code using a just in time compiler and messing with their internal variables would be

问题 I'm reading STL source code and I have no idea what && address operator is supposed to do. Here is a code example from stl_vector.h : vector& operator=(vector&& __x) // <-- Note double ampersands here { // NB: DR 675. this->clear(); this->swap(__x); return *this; } Does "Address of Address" make any sense? Why does it have two address operators instead of just one? 回答1: This is C++11 code. In C++11, the && token can be used to mean an "rvalue reference". 回答2: && is new in C++11. int&& a means

问题 I'm reading STL source code and I have no idea what && address operator is supposed to do. Here is a code example from stl_vector.h : vector& operator=(vector&& __x) // <-- Note double ampersands here { // NB: DR 675. this->clear(); this->swap(__x); return *this; } Does "Address of Address" make any sense? Why does it have two address operators instead of just one? 回答1: This is C++11 code. In C++11, the && token can be used to mean an "rvalue reference". 回答2: && is new in C++11. int&& a means

问题 In a reputable source about C, the following information is given after discussing the & operator: ... It's a bit unfortunate that the terminology [address of] remains, because it confuses those who don't know what addresses are about, and misleads those who do: thinking about pointers as if they were addresses usually leads to grief... Other materials I have read (from equally reputable sources, I would say) have always unabashedly referred to pointers and the & operator as giving memory

问题 In Bjarne Stroustrup's book "The C++ Programming Language (4th Edition)" on p. 267 (Section 10.4.5 Address Constant Expressions), he uses a code example where the address of a local variable is set to a constexpr variable. I thought this looked odd, so I tried running the example with g++ version 7.3.0 and was unable to get the same results. Here is his code example verbatim (although slightly abridged): extern char glob; void f(char loc) { constexpr const char* p0 = &glob; // OK: &glob's is