array of char*

piul

Hi there! I need an array of strings of char * type and I am not clear about how to free up memory after use. The code below does not work.

char \* ptr\_p\_c\[3\];
ptr\_p\_c\[0\] = new char;
strcpy (ptr\_p\_c\[0\], "hi there");
ptr\_p\_c\[1\] = new char;
strcpy (ptr\_p\_c\[1\], "whatever");

delete ptr\_p\_c;

I know I shouldn't be using this type for strings and all this. Believe me, I've tried repeatedly to convince my customer this is not the right way to do things, but unfortunately it is not my decission... Thanks a lot.

Lost User

First up, the "customer" has no business wrt such low level programming details. I smell something else here. Anyway, to the point, the allocation itself is flawed. You are allocating just one character and copying several characters into it. A lot of corrupted memory. The delete will cry. The proper way to delete is to loop through the array and delete every allocated sub array.

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piul

Something like this??

const int num = 3;
char \* ptr\_p\_c\[num\];
for (int i = 0; i<num; i++)
	ptr\_p\_c\[i\] = new char\[20\];

strcpy\_s (ptr\_p\_c\[0\], 9, "hi there");
strcpy\_s (ptr\_p\_c\[1\], 7, "change");

for (int i = 0; i<num; i++)
	delete ptr\_p\_c\[i\];

CPallini

Well, you already know that avoiding std::string is just plain silly so I don't bother you more:

char * ptr_p_c[2];
ptr_p_c[0] = new char[sizeof("hi there")];
strcpy (ptr_p_c[0], "hi there");
ptr_p_c[1] = new char[sizeof("whatever")];
strcpy (ptr_p_c[1], "whatever");
delete ptr_p_c[0];
delete ptr_p_c[1];

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

Lost User

better

const int N = ??
const char* names[N] = {"...", "...", ...}
char *arr[N];
for(n=0;n
...byte till it megahertz...

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T2102

Agreed. Use std::string or you can use one of many already existing string classes. You also could create an array of char[] if you have a series of strings whose length the compiler can computebv in advance.

David Crow

Does the memory for those strings necessarily need to come from the heap? If not, what about:

char *ptr_p_c[] = { "hi there", "whatever" };

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Maximilien

piul wrote:

Believe me, I've tried repeatedly to convince my customer this is not the right way to do things, but unfortunately it is not my decission...

If you are a professional, then MAKE IT your decision. if it takes less time to develop, less time to debug, make the code more secure and readable, than you need to do it the right way. anyway,you should delete each item in the ptr_p_c array. good luck.

Watched code never compiles.

Lost User

piul wrote:

Believe me, I've tried repeatedly to convince my customer this is not the right way to do things

Why does the customer need to know how you are implementing a small piece of code? If they understand that level of detail then why do they need you?

Just say 'NO' to evaluated arguments for diadic functions! Ash

_Superman_

I know dumb customers. I also know dumber customers. But this is the dumbest customer.

«_Superman_» _I love work. It gives me something to do between weekends.

_Microsoft MVP (Visual C++)

Polymorphism in C

CPallini

Because he's afraid of using new for instancing strings. :rolleyes:

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

CPallini

You know dumb customers. I know dumb customers. He knows dumb customers. Hey Superman, your customers. Hey Superman, YOUR customers are just not that dumb. :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

Lost User

So dumb customers are your kryptonite, eh?

...byte till it megahertz... my donation to web rubbish

_Superman_

A good reason to dislike them. :)

«_Superman_» _I love work. It gives me something to do between weekends.

_Microsoft MVP (Visual C++)

Polymorphism in C

Alan Balkany

It looks like your sample is an example of why std:::string should be used: The null terminator will overflow the char[] buffers you allocated by one byte.

CPallini

You're wrong. Hint: I didn't use strlen. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

Alan Balkany

Oops, I stand corrected.