compiler error

[jamescai]

Hello All,

I got compiler error for my c++ structure,

struct LTestString
{
int len;
char str[];
};

LTestString s = {3, "ab"};

the error message is: error: initializer-string for array of chars is too long.
I need to use char str[] of dynamic size. I used gcc 4.1.2
BTW, it works in windows environment.

Thanks!
James

[talowe]

Hello All,

I got compiler error for my c++ structure,

struct LTestString
{
int len;
char str[];
};

LTestString s = {3, "ab"};

the error message is: error: initializer-string for array of chars is too long.
I need to use char str[] of dynamic size. I used gcc 4.1.2
BTW, it works in windows environment.

Thanks!
James


char* str;

instead of


char str[]

works. But why not


#include <string>
using std::string;

string s="ab";

[hod139]

Replacing char[] with char* will cause a memory leak, and probably a difficult to debug segfault later on since you haven't allocated the memory for the string. If you used char* you would need to write something like:


struct LTestString
{
explicit LTestString(int _len, const char * const _str)
{
len = _len;
str = new char[_len];
strncpy(str, _str, len-1);
str[len-1] = '\0'; // Just in case str is longer than len
}
~LTestString()
{
if(str)
delete[] str;
}

int len;
char *str;
};


int main(void){
LTestString s(3, "ab");

return 0;
}
If this is C++, why not use std::string as talowe suggested?

[jamescai]

Thank you for your reply. Since I port windows app to linux, I can't change too much source codes. I need to keep this structure. Any other solutions?

Thanks!
James

[Lux Perpetua]

Well, FYI,
char str[]; is not a valid C++ declaration, so something's gotta give.

[hod139]

Well, FYI,
char str[]; is not a valid C++ declaration, so something's gotta give.
You can use the
char str[] declaration only if you know the size of the array at comile time, for example


char str[] = "ab";
is perfectly legal, since the size of str can be determined. If the size is unknown, then dynamic memory allocation is required, which is the solution I posted earlier.


I need to keep this structure. Any other solutions?

As was stated earlier, since this is C++ why not replace the character array with a std::string?


#include <string>

struct LTestString
{
int len;
//char str[];
std::string str;
};

LTestString s = {3, "ab"};