I have this code which works. But I’m confused about how pointer arrays work, dont you have to initialise the array? How is this block of code able to just have ‘&arr[i]’. Secondly, why don’t we need to derefernce the pointer to manipulate the data stored in the location the pointer is pointing to (the… Read More Arrays and pointers in C using Malloc

I am allocating a struct with a function pointer. Obviously, I have to free the struct at the program end. However, freeing a function pointer leads to undefined behavior. How should I do it? I tried to create a pointer to this pointer to a function point but it does not work, right? Attached a… Read More How to free a struct with a function pointer member?

This is my struct. typedef struct { uint8_t *data; size_t size; } buffer; I initialize it like this in my main function. buffer *array; array = calloc(255, sizeof(*array)); //check for error for (int i = 0; i < 255; i++) { array[i].data = malloc(sizeof(*array->data)); //check for error } Then I pass it to a function.… Read More Passing an array of structs where one of the fields is another array, to a function

I have the following code, and am specifically having problems with the print_file_results function. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <getopt.h> int bytes_flag,lines_flag, words_flag; int arg_in; static struct option long_opts [] = { {"bytes", no_argument, 0, ‘c’}, {"lines", no_argument, 0, ‘l’}, {0,0,0,0} }; int count_bytes(const char *filename){ FILE * file_stream; int byte_count = 0;… Read More malloced char * object filled with random text and of an apparent different size

I am trying to append a struct pointer to a dynamically allocated array. After that I return the struct pointer that was added to the array. This is then dereferenced and put into a variable that I want to print out. My problem is that when I try to access a value (i.e. struct.id) the… Read More What is the meaning of `malloc(): corrupted top size`

I want to write a program that will allocate some chunk of memory every second, and then write out how much memory is left (I intentionally do not free any memory as the actual use case for this is simulating out of memory situations). Here is the program (for linux): #include <stdio.h> #include <sys/types.h> #include… Read More How to determine available heap memory in a C/C++ program

In this video it is mentioned that the compiler can assume that malloc never returns NULL and is allowed to optimize accordingly. I have never heard of this and couldn’t find any reference to it in the C-Standard. Can anyone tell me if this is true and if so, where this behaviour is specified? The… Read More Can the compiler assume that malloc will never return NULL?

I am always told to not allocate memory whenever I can achieve the exact same thing without it. Do people say that because freeing things in your code can take some time, or is there an efficiency-oriented explanation? (e. g. better performance) >Solution : Because managing memory is complicated and prone to all kinds of… Read More Why do I always hear to avoid allocating memory when I can in C?

I was running this code to expect an error but to my surprise, it didn’t. Even if I initialize a string*(5 bytes)* that is greater than what was allocated using malloc (4bytes). #include <stdio.h> #include <stdlib.h> #include <string.h> int main() { char * name = malloc(4); name = "hello"; printf("%s\n",name); return 0; } This is… Read More C code not throwing error for initializing extra string character than it is supposed to be

Full code: #include <stdio.h> #include <stdlib.h> #include <string.h> void printarray(int* array, int arraysize){ for (int i = 0; i<arraysize; i++){ printf("%d\n", *array); array++; } } void printStrArray(char** array, int arraysize){ int j = 0; for (int i = 0; i<arraysize; i++){ j = 0; while (array[i][j] != ‘\0’){ printf("%c", array[i][j]); j++; } printf("\n"); } }… Read More looping array of pointers to free them makes program crash in c