You did not show the code which adds the Child*s to the vector, but the symptoms you describe provide compelling evidence that you used pointers to some kind of local or temporary objects, which go out of scope (are destroyed) while the vector still holds the pointers. Your program hangs as a result of using … Read more
There is a huge mess there, you need to get used to pointers! Ok so your function gets g and p which are int *. What you give them is &g and &p, where g and p are also int *. So you pass to your function type int **. Also g[i+3] is *(g+i+3) so … Read more
The ampersand (&) in a declaration declares a reference type, not a pointer. The ampersand (&) in an expression is the address of operator, which yields a pointer. Just because the same token is used in the language for two different things does not mean they are related things. Unfortunately, especially for learners. 0 solved … Read more
Let’s try to explain *x = *y; without using the word “dereference”: *x represents the integer object pointed to by x. As it is the left operand of the assignment, it means that this integer object is going to be updated. *y represents the integer object pointed to by y. As it is the right … Read more
I am not sure what you are asking, But the following program meets your conditions, 1. there is array of pointers 2. there is malloc 3. there is no character array #include <stdio.h> #include <stdlib.h> #define STR_MAX_SIZE 256 int main() { char *str; char *pos[2]; char c; if((str = malloc(STR_MAX_SIZE)) ==NULL) { return -1; } … Read more
Consider the case when you insert at the end of the list. Then you get // current = NULL current->next = nextnode; // is ((struct node*)NULL)->next = nextnode; solved I am getting Segmentation fault (core dumped) for below code.Please help me out [closed]
double* ptr; ptr = (double*)malloc(10*_R_CONST*sizeof(double)+2048); This is the C way of allocating an array dynamically at runtime, the Java equivalent is double[] ptr = new double[10*_R_CONST+256]; (Note that Java does not need the sizeof(double) factor, since it allocates objects, not bytes. For the same reason, the 2048 byte buffer shrinks to 256 doubles.) Similar, the … Read more
This turned out to be either a bug in the core library or a very misguided documentation, depending on the perspective (issue #29850). The behavior of the function unsafe_convert changed from version 0.4 to 0.5, in a way that makes it more flexible than what is currently suggested. According to this commit, unsafe_convert changed from … Read more
Java doesn’t use pointers, but uses references. NullPointerException is a way to say that an attempt is made to send a message (invoke a method) using reference which doesn’t point to any object. It has nothing to do with pointers in the sense of C/C++. solved What does null pointer exception mean in error messages? … Read more
Well the simple thing is here you would be good to go even if you didn’t use casting in these 2 statements char** sa = (char**)a; char** sb = (char**)b; Because conversion from void* to char** is implicit. This would also be fine (provided you assign it to correctly qualified variable name). const char** sa … Read more
#include <stdio.h> int main () { int v[5]; int *z = &v[0]; // z points to v[0] *z=12; // v[0] = 12 z++; // z points to v[1] now *z=16; // v[1] = 16 z++; // z points to v[2] now *z=-3; // etc z++; // etc *z=25; // etc } solved Can someone explain … Read more
Your second program is malformed. It’s not using std::string::operator[] at all. string * ps = new string(str); ps[0] = ‘n’; Not only does std::string support the [] operator, every pointer to a type also supports the [] operator. It’s how C style arrays work, and it’s what you’re doing in the code above. ps isn’t … Read more
Woo, it’s been a long time since I dealt with C pointers, but let me see if I can help. Coordinate_T *p; declares a pointer to a Coordinate_T struct. We don’t have any memory available yet, we just have a pointer to… nothing. p = (Coordinate_T *)malloc(sizeof(Coordinate_T)) actually allocates the memory for us. Now p … Read more
The std::vector<float> class is a class and not a pointer. I think your teacher wants to discourage you from using the c-style arrays: float* array = new float[200]; This might be because using this you have to remember to delete them later: delete[] array; The vector<float> will handle this for you. Plus gives you nice … Read more
how to clear pointer variable which is holding start of memory location that needs to be cleared for 20 bytes of data from starting location [closed] solved how to clear pointer variable which is holding start of memory location that needs to be cleared for 20 bytes of data from starting location [closed]