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

I want to copy the string “Best School” into a new space in memory, which of these statements can I use to reserve enough space for it A. malloc(sizeof(“Best School”)) B. malloc(strlen(“Best School”)) C. malloc(11) D. malloc(12) E. malloc(sizeof(“Best School”) + 1) F. malloc(strlen(“Best School”) + 1) I am still very new to C programming… Read More Right methods of copying strings with malloc

So when I pass a data type like a struct to assign some memory to it I find that the pointer doesn’t change within the main scope. This further becomes a problem when I try to free the memory but obviously if its using the original pointer it will be pointing at the stack address.… Read More Malloc within function not changing pointer value

The Problem I was having some troubles with a library, wich makes use of flexible array members. There is no issues to allocate the object, but i can’t reliably free it. Whenever the object has to be resized or free’d, using free() or realloc(), valgrind outputs errors of reads of uninitialized values, invalid free() calls,… Read More Two functions with exact same definition gives different results on valgrind. Dynamic Memory Alocation

I am writing a function where I need to call malloc multiple times to allocate memory for very small arrays dynamically (like 4-5 ints). These arrays are used to store different types of datatypes. so I thought of allocating a large memory and use it for all types. Here is what I am trying to.… Read More Can we use single malloc() block to represent two different types?

#include <iostream> #include <vector> #include <algorithm> using namespace std; vector<vector<float>> func(int M) { // res = matrix size MxM vector<vector<float>> res; float* buffer = static_cast<float*>(malloc(M * M * sizeof(float))); res.reserve(M); for (int i=0; i<M; i++) { res.emplace_back(buffer + i * M, buffer + (i + 1) * M); /// res[i] = compute_the_matrix(); } return res;… Read More C++ using vector<vector> to represent matrix with continuous data buffer

I’m working on a case where I’m dynamically populating a char array based on the return value of another function. At some point, I would like to compare the incoming value to a static string and trigger an action. For some reason, I couldn’t get the strcmp function to work. Please see the code below… Read More Comparing dynamically allocated strings in C