I can not properly free up the memory, help.

//создаем многомерный массив указателей, каждый их который будет хранить информацию об одном человеке int person_num = 1; char ***full_info = new char**[person_num]; for (int i = 0; i < person_num; i++){ full_info[i] = new char *[5]; for (int j = 0; j < 5; j++){ full_info[i][j] = new char[10]; } } full_info[0][0] = "Sidorow"; full_info[0][1] = "Ivan"; full_info[0][2] = "24"; full_info[0][3] = "1987"; full_info[0][4] = "Filatova 20"; person_num++; //чтобы добавить человека увеличиваем размер массива //создать новый массив указателей char ***temp_full_info = new char**[person_num]; for (int i = 0; i < person_num; i++){ temp_full_info[i] = new char *[5]; for (int j = 0; j < 5; j++){ temp_full_info[i][j] = new char[10]; } } //скопировать старый массив указателей в новый for (int i = 0; i < person_num - 1; i++){ for (int j = 0; j < num_of_colls; j++){ temp_full_info[i][j] = full_info[i][j]; } temp_full_info[i] = full_info[i]; } //освобождение памяти for (int i = 0; i < person_num - 1; i++){ for (int j = 0; j < num_of_colls; j++){ delete full_info[i][j]; } delete[] full_info[i]; } delete[] full_info;
  • In C ++, a multidimensional array of strings is vector<vector<string>> , not char*** . - VladD

2 answers 2

In these cycles

 char ***full_info = new char**[person_num]; for (int i = 0; i < person_num; i++){ full_info[i] = new char *[5]; for (int j = 0; j < 5; j++){ full_info[i][j] = new char[10]; } }

You dynamically allocated arrays at three levels:

 char ***full_info = new char**[person_num]; full_info[i] = new char *[5]; full_info[i][j] = new char[10];

Therefore, on each of these levels you need to free the allocated memory.

Then you have a suggestion in the program.

 full_info[0][0] = "Sidorow"; full_info[0][1] = "Ivan"; full_info[0][2] = "24"; full_info[0][3] = "1987"; full_info[0][4] = "Filatova 20";

String literals have a static memory duration. That is, they are distributed by the compiler at the stage of compilation in a static memory area ..

So in the above cycles, you have allocated memory.

 full_info[i][j] = new char[10];

This means that the full_info[i][j] pointers point to the first bytes of the selected character arrays char[10] . However, you then rewrite the values ​​of these pointers with the addresses of string literals like, for example, full_info[0][0] = "Sidorow"; , and, thereby, lose addresses of the selected character arrays in the above cycle. As a result, you have a memory leak. You will not be able to correctly free all the allocated memory, because the addresses of the selected character arrays have been lost.

It would be correct to copy string literals into selected arrays, such as

 std::strcpy( full_info[0][0], "Sidorow" );

However, you have insufficiently allocated character arrays and, for example, this string literal "Filatova 20" , which has type const char[12] does not fit in an array of type char[10] .

Keep in mind that in these cycles

 //скопировать старый массив указателей в новый for (int i = 0; i < person_num - 1; i++){ for (int j = 0; j < num_of_colls; j++){ temp_full_info[i][j] = full_info[i][j]; } temp_full_info[i] = full_info[i]; }

you also copy the pointers themselves instead of copying the contents of character arrays of the "lower" level. As a result, you again have a memory leak.

With regard to the release of memory, the memory allocated in the above cycles, is released in reverse order.

 for (int i = 0; i < person_num; i++){ for (int j = 0; j < 5; j++){ delete [] full_info[i][j]; } delete [] full_info[i]; } delete [] full_info;

If you have values ​​of the number of elements of the arrays, respectively, equal to the values ​​of 5 and 10 (or a slightly larger value), are constant, then you could do it easier. for example

 char ( *full_info )[5][10] = new char[person_num][5][10];

Then it will be very easy to delete the allocated memory.

 delete [] full_info;

Instead of manually allocating and freeing memory, you could use the standard std::vector and std::string classes.

For example,

 std::vector<std::vector<std::string>> full_info( person_num, std::vector<std::string>( 5 ) ); 
     full_info[i][j] = new char[10];

    Here you have allocated a memory ... and right there

     full_info[0][0] = "Sidorow";

    lost her forever. You no longer have a pointer to the allocated memory! You have a pointer to a static string ...

    To copy strings, use strcpy - and you will succeed. You do not copy the contents of the lines, but the pointers, and this is your whole mistake. And then you try to delete the memory that no one allocated ...