dinamyc vector of pointers

[Antonio]

Hello, I've tryed to assign fields in a string to the element of a vector of pointers to char. Because the number of fields in the string is unknown I've declared a vector of pointers, Fields=new char *[], and for each field in the string a pointer to char, Field[i]=new char [Field_Len]. When program show the content of each element, all element have the right string except the first one which contains a wrong string. Some can help me to understand way?
The problem disappears if I allocate memory for a defined number of element, Fields=new char *[20]: in this case the first element is shown correctly; in this case, if the number of fields in the string exceed 20 can I add more elements to Fields using the new operator?

Thanks a lot for your help.

[anders43]

so you have declared an array of char pointers but you haven't allocated memory for the array itself (the new char *[] doesn't do the trick), when you later write Fields[i] = new char [Field_Len] you are doing something naughty

I would propose instead that you use std::vector instead, it easier to use and safer:

#include <vector>

std::vector<string> Fields;

Fields.push_back( "some string" );
Fields.push_back( "someother string" );


cout << Fields[0] << endl;

[Antonio]

Hi anders43, I'm going to study the class <vector> as you suggested , but what is naughty and why in that I did. Can you tell me if the length of object defined as vector may be extended as needed? once program has allocated memory for a given number of element, is it possible to allocate memory for other additional elements?

Thanks for your answers.

[Bazzy]

There is the resize function for that
http://www.cplusplus.com/reference/stl/vector/resize.html