pointers

问题 I have a Class, it will be implemented to be many instances. I want to keep connections between some of the instances, and pass messages among them. In C++, I can do this like: class A { A (*connections)[]; int sum; public: void pass(int index) { connections[index] -> receive(sum); } void receive(int input) { sum += input; } } Then I only need to add pointers of other instances to connections[] , I can pass messages among them with each other. Currently I have to use Python doing this, but

问题 I have a malloced string that I needed to parse. I did all of the parsing using strtok() . Strtok has returned a pointer to me and if I printf using that pointer the correct part of the parsed string gets printed. Afterwards I will be freeing the malloced string that the pointer returned by strtok was pointing too. How do I store what the pointer was pointing at into a struct such that the value remains in the struct variable even after the main string has been freed. String: Tommy-1234567 My

问题 Here is my program: package main import ( "fmt" ) type Number struct { val int } func (num * Number) Increment () { num.val += 1 } func (num Number) Value() int { return num.val } func main() { numbers := []Number { {val: 12}, {val: 7}, {val: 0}, } for _, each := range numbers { each.Increment() fmt.Println(each.Value()) } for _, each := range numbers { fmt.Println(each.Value()) } } Here is the output: 13 8 1 12 7 0 First question: why does the Increment() method not update the value in the

问题 Here is my program: package main import ( "fmt" ) type Number struct { val int } func (num * Number) Increment () { num.val += 1 } func (num Number) Value() int { return num.val } func main() { numbers := []Number { {val: 12}, {val: 7}, {val: 0}, } for _, each := range numbers { each.Increment() fmt.Println(each.Value()) } for _, each := range numbers { fmt.Println(each.Value()) } } Here is the output: 13 8 1 12 7 0 First question: why does the Increment() method not update the value in the

问题 int main(void) { int n1 = 2, n2 = 5; int *p = &n1, *q = &n2; *p = *(q++); printf("%d,%d", *p, *q); return 0; } output= 5,5 Why the value of *q is 5 it should have some garbage value? int main(void) { int n1 = 2, n2 = 5; int *p = &n1, *q = &n2; *p = *(++q); printf("%d,%d", *p, *q); return 0; } output= 2,2 And how is this happening? Can anyone explain how precedence rule works in pointers? 回答1: *p = *(q++); is (more or less) equivalent to *p = *q; q++; , so p is fine. q++ will be evaluated,

问题 I have an array of bytes aka unsigned char called content . I want to split my content array into 2 new arrays in a separate function. This function should also determine the size for each of the 2 chunks and allocate memory for them. Also, I want to be able to use both the new arrays and their sizes outside of the function. My implementation is giving me segmentation fault and I must be doing something with pointers wrong. Main function int main(int argc, char *argv[]) { byte *content = NULL

问题 This question already has answers here : Are a, &a, *a, a[0], &a[0] and &a[0][0] identical pointers? (8 answers) Closed 6 years ago . I got the output for the following code as -> 6 I was confused by the output, so I changed a small portion of code and checked it. I substituted this int * ptr=(int*)(a+1) for the Not clear statement, I got the output as --> 1 . How? I heard &a , a , a[0] all are same address? what makes it different? #include<stdio.h> int main() { int a[] = {1, 2, 3, 4, 5, 6};

问题 I'm trying to swap out the contents of a method at runtime for the purposes of unit testing legacy code. I've been working with these SO answers; Dynamically replace the contents of a C# method? How to replace the pointer to the overridden (virtual) method in the pointer of my method? (Release x64 and x86) Here's a full code sample of what I have so far. using System; using System.Diagnostics; using System.Reflection; using System.Runtime.CompilerServices; namespace Foo.Bar { public interface

问题 I saw on this website that this: fscanf(fin, "%[^\n]", &p); could be used for reading from my input file( fin ) into that char type pointer( *p ) all the characters until the first enter hit. At some inputs it works properly, but at others it doesn't. This is the input I should process and I cannot: (((zahar 100 ou 3) 5 unt 100 nuca 200) 4 (lapte 200 cacao 50 zahar 100)3)20 This is my whole code: #include <string.h> #include <stdio.h> FILE *fin, *fout; int main() { fin = fopen("reteta.in", "r

问题 I saw on this website that this: fscanf(fin, "%[^\n]", &p); could be used for reading from my input file( fin ) into that char type pointer( *p ) all the characters until the first enter hit. At some inputs it works properly, but at others it doesn't. This is the input I should process and I cannot: (((zahar 100 ou 3) 5 unt 100 nuca 200) 4 (lapte 200 cacao 50 zahar 100)3)20 This is my whole code: #include <string.h> #include <stdio.h> FILE *fin, *fout; int main() { fin = fopen("reteta.in", "r