c - Malloc, free and segmentation fault -

i don't understand why, in code, call "free" cause segmentation fault:

#include <stdio.h> #include <string.h> #include <stdlib.h>  char *char_arr_allocator(int length);  int main(int argc, char* argv[0]){      char* stringa =  null;     stringa = char_arr_allocator(100);       printf("stringa address: %p\n", stringa); // same address "arr"     printf("stringa: %s\n",stringa);     //free(stringa);      return 0; }  char *char_arr_allocator(int length) {     char *arr;     arr = malloc(length*sizeof(char));     arr = "xxxxxxx";     printf("arr address: %p\n", arr); // same address "stringa"     return arr; } 

can explain me?

thanks, segolas

you allocating memory using malloc correctly:

arr = malloc(length*sizeof(char)); 

then this:

arr = "xxxxxxx"; 

this cause arr point address of string literal "xxxxxxx", leaking malloced memory. , calling free on address of string literal leads undefined behavior.

if want copy string allocated memory use strcpy as:

strcpy(arr,"xxxxxxx");