Advertisements I have a matrix stored in a float array, and I need to swap a row of one matrix into another. This is what I have done so far. The matrices m and m_new are a matrix class, where, ‘float* m = new float(N*N)’ is the class variable ‘m’. I made a pointer to… Read More Row swap a float array in C++

Advertisements // pointer of array #include<stdio.h> int main() { int arr[] = { 3, 5, 6, 7, 9 }; int *p = arr; int (*ptr)[5] = &arr; printf("p = %p, ptr = %p\n", p, ptr); printf("*p = %d, *ptr = %p\n", *p, *ptr); printf("sizeof(p) = %lu, sizeof(*p) = %lu\n", sizeof(p), sizeof(*p)); printf("sizeof(ptr) = %lu, sizeof(*ptr)… Read More Why in this program size of integer is 8?

Advertisements I’m trying to assign the value of 0x0010 to pointer ptr1 in the following code that demonstrates how pointers interact with addition/subtraction: #include <stdio.h> int main(void) { int * ptr1=0x0010; double * ptr2=0x0010; printf("%p %p\n", ptr1+1, ptr1+2); // Increment by 4 then 8 printf("%p %p\n", ptr2+1, ptr2+2); // Increment by 8 then 16 printf("%p… Read More Error: invalid conversion from 'int' to 'int*' [-fpermissive] while initialising pointer address

Advertisements I understand that a pointer to const is a pointer through which the value of the variable that the pointer points cannot be changed. Therefore, in the following example, I expect the compiler to raise an error: int main() { int a = 42; const int *ptr = &a; ptr[0]++; return 0; } Now,… Read More Pointer to const: why is ptr[1] also read-only?

Advertisements As I understand it, you can’t return an array from a method because you are actually returning a pointer to data created in the method’s scope. There’s no guarantee that the data will still be at the address pointed to by that pointer outside the method scope. But it seems to work for constructors… Read More Is any copying happening here?

Advertisements I was trying to remind how pointers worked in c and c++ and I found this very interesting video (Pointers in C/C++). In minute 3:14:00, he begins to talk about pointer functions and callbacks, and I ended a bit confused about the real application of them. The example case he provides consists of a… Read More Function pointers and callbacks in c/c++

Advertisements #include "stdio.h" int printsomething(int *array, int arrayreturn[5]) { int i; for(i = 0; i < 10; ++i) { printf("%d\n", array[i]); } for(i = 0; i < 5; ++i) { int &arrayreturn[i] = {i}; } return 0; } int main() { int array[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; //… Read More Error expected identifier or '(' int &arrayreturn[I] = {I}

Advertisements This is an exercise from the book C Programming: A modern approach by K.N King "Assume that the following array contains a week’s worth of hourly temperature readings, with each row containing the readings for one day: int temperatures[7][24]; Write a statement that uses the search function to search the entire temperatures array for… Read More How to send 2d-array as argument to function that expects 1d-array in C?

Advertisements maybe one of you can help me. I don’t know what to do anymore. I have the following test code: #include <stdio.h> int main() { unsigned int block = 0; unsigned int alp = 0; char *input ="test"; unsigned int *pt = NULL; pt = (unsigned int*)input; alp |= ((*pt) >> 8); printf("pointer value:\t… Read More pointer cast issue (C)

Advertisements What is the deference between passing array this way: static char arr[N]; void func(void *buf, size_t size) { // … } int main(void) { func(arr, N); // … } And this way: // … int main(void) { func(&arr, N); // … } Is there any deference in those listings? It seems that the 2nd… Read More Pass array to a function as a pointer and value