char ** initialization and store values

tagopi

Hello Everybody, I am trying to pass some values to char ** (to a third party library). But i am getting some issue in that.

    char\*\* ids = new char\*\[m\_Size\];
    for(int i=0; i

using that third party function, its creating an output file and in that file the stored value is showing like this.

GROUP : 46,0
GROUP : 44,0
GROUP : 42,0
GROUP : ÝÝÝÝÝÝÝÝ†«ãe,0
GROUP : 40,0
GROUP : 38,0

But if I give values like this, then in output file, the values are showing fine.

char* ids[6] = {"38", "40", "42", "44", "46", "48"};

in the output file,

GROUP : 38,0
GROUP : 40,0
GROUP : 42,0
GROUP : 44,0
GROUP : 46,0
GROUP : 48,0

(see the sequence also)

what i am doing wrong? initialization ? or passing values ?

Thanks,
A. Gopinath.

Jochen Arndt

The code looks fine. Because only one of the strings from your array returns wrong data, this element may be corrupted somewhere else. Note also that you must call ReleaseBuffer() for each string array element after calling the library function. If not doing so, further accesses may return invalid data. You should also check the documentation of the library if the passed strings are constant or may be changed. If they may be changed, you must pass the max. allowed length to GetBuffer().

Lost User

char** ids = new char*[m_Size]; Here you create an array of char pointers. Here: ids[i] = you need to create an aray of chars, so it should be ids[i] = new char [] Then copy the data into the char array.

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_Superman_

In the first case, the pointers are pointing to memory maintained by the CStringArray class. It is likely that CStringArray relocated, resized or moved the memory around. So you need to allocate memory for each pointer and copy the contents to the allocated memory. In the second case you have pointers to fixed locations that do not change.

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

_Microsoft MVP (Visual C++) (October 2009 - September 2013)

Polymorphism in C

Lost User

I am aurpsised it even runs with out crashing since he is setting his array pointers to the values contained in some string! So if the string was 'this monkley is stupid' the first pointer will have the value of the ASCII codes for 'this', the second pointer ' mon' and so on. Of course these addresses are completely invalid and point to somewhere in his process. If he manipulated them in any way its bye bye process time!

============================== Nothing to say.