malloc

问题 I need to create a program which calculates the cumulative sum of a dynamically allocated vector and the vector should be filled with random values (not values from stdin) ​​using only pointers . I couldn't think of a version that uses only pointers (i'm kinda new to this matter). This is the code I have so far: #include <stdio.h> #include <malloc.h> int main() { int i, n, sum = 0; int *a; printf("Define size of your array A \n"); scanf("%d", &n); a = (int *)malloc(n * sizeof(int)); printf(

问题 On accessing a struct member of type std::string, the error Bus Error: 10 popped up. Code is as following. #include <iostream> #include <string> struct KeyValuePair { std::string key; std::string value; }; struct KeyValuePair *temp = (struct KeyValuePair *) malloc(sizeof(struct KeyValuePair)); int main(void) { temp->value = "|"; temp->value += "someval|"; std::cout << temp->value << std::endl; return 0; } Running gdb on the code shows the following at the line temp->value = "|" . Program

问题 for learning purpose I'm implementing a stack with it's functions in c. I added some small additional functionality to use malloc the first time and try to understand it properly. I wrote a function which is initially creating my stack struct. The return value of the function is a new struct with an already allocate memory. What is the best way to handle a malloc exception in a function which return value should be a struct? Maybe should I design the function different? I'm aware that the

问题 for learning purpose I'm implementing a stack with it's functions in c. I added some small additional functionality to use malloc the first time and try to understand it properly. I wrote a function which is initially creating my stack struct. The return value of the function is a new struct with an already allocate memory. What is the best way to handle a malloc exception in a function which return value should be a struct? Maybe should I design the function different? I'm aware that the

问题 quick question Can you use the free() function without having to prior call a malloc ?? ei. void someFunc( void ) { char str[6] = {"Hello"}; //some processing here .... free(str); } I get no compiling errors but Does this work or is it correct at all ? Thank you, 回答1: This is not at all correct: You cannot free a static array such as char str[6] . free() should only be called on memory you allocated (or on NULL). 回答2: When you call malloc() or any other allocation function, memory will be

问题 I want to make an array of string using malloc, and then clear ALL the allocated memory, I believe that I use malloc correct but I can't understand what I'm doing wrong when I try to clear it: #include <stdlib.h> #include <stdio.h> #include <string.h> void print_arr(char* arr[]); void clear_arr(char* arr[], int size); int main() { int number = 10; char **myarr = malloc((number+1)*sizeof(char*)); for (int i = 0; i <= number; i++) { myarr[i]=NULL; } for (int i = 0; i < number; i++) { char str[]

问题 I want to make an array of string using malloc, and then clear ALL the allocated memory, I believe that I use malloc correct but I can't understand what I'm doing wrong when I try to clear it: #include <stdlib.h> #include <stdio.h> #include <string.h> void print_arr(char* arr[]); void clear_arr(char* arr[], int size); int main() { int number = 10; char **myarr = malloc((number+1)*sizeof(char*)); for (int i = 0; i <= number; i++) { myarr[i]=NULL; } for (int i = 0; i < number; i++) { char str[]

问题 I want to make an array of string using malloc, and then clear ALL the allocated memory, I believe that I use malloc correct but I can't understand what I'm doing wrong when I try to clear it: #include <stdlib.h> #include <stdio.h> #include <string.h> void print_arr(char* arr[]); void clear_arr(char* arr[], int size); int main() { int number = 10; char **myarr = malloc((number+1)*sizeof(char*)); for (int i = 0; i <= number; i++) { myarr[i]=NULL; } for (int i = 0; i < number; i++) { char str[]

问题 I want to make an array of string using malloc, and then clear ALL the allocated memory, I believe that I use malloc correct but I can't understand what I'm doing wrong when I try to clear it: #include <stdlib.h> #include <stdio.h> #include <string.h> void print_arr(char* arr[]); void clear_arr(char* arr[], int size); int main() { int number = 10; char **myarr = malloc((number+1)*sizeof(char*)); for (int i = 0; i <= number; i++) { myarr[i]=NULL; } for (int i = 0; i < number; i++) { char str[]

问题 For the code below: (1) "main" calls a function "f1". (2) function "f1" does some number crunching; creates an array of "char" with malloc and then, returns the pointer of the array to the main (without de-allocating -freeing- the array). I have 3 questions related to the case: (1) I assume, although the function "f1" has terminated, the allocated char array still stays allocated until the main program terminates completely. That is, the allocated memory still belongs to the main and no other