c - 程序内存泄漏？ C

Question

动态分配一个cstrings数组来分隔传递给它的字符串。 Valgrind 说我有 7 个分配，但只有 3 个释放。但我不确定如何在使用返回数组的函数时释放内存。

这是函数

char ** func( char * str, char del ) {
     char** substrings;
     char* word;
     int len = 0, capacity = 2, i, x;
     substrings = malloc(sizeof(char*) * (capacity + 1));
     for (i = 0; i <= capacity; i++){
         substrings[i] = NULL;
     }
     while (*word != '\0') {
         if (len  >= capacity){
             /* double size */
             char **temp;
             capacity *= 2;
             temp = malloc(sizeof(char*) * (capacity + 1));
             for (i = 0; i < len; i++) {
                 temp[i] = substrings[i];
             }
             for (i = len; i <= capacity; i++) {
                 temp[i] = NULL;
             }
             substrings = temp;

             temp = NULL;
             free(temp);

         }
     }     
     return substrings;
 }

Answer 1

根据您的代码，

if (len  >= capacity){
         /* double size */
         char **temp;
         capacity *= 2;
         temp = malloc(sizeof(char*) * (capacity + 1));
         for (i = 0; i < len; i++) {
             temp[i] = substrings[i];
         }
         for (i = len; i <= capacity; i++) {
             temp[i] = NULL;
         }
         free(substrings); // release old memory
         substrings = temp; // this line causes substrings pointer leak if you assign new address to it without free

         temp = NULL;
         free(temp); // no need free NULL

     }

实际上，如果您将 valgrind 与 --track-origins=yes 选项一起使用，它会报告哪条线路发生泄漏。