Pointer to pointer to const conversions

[James Aguilar]

Quick question. Why, in the following code sample, can I not convert a
char ** to a const char **?

void test(const char **p)
{
cout << str(*p) << '\n';
}

int main()
{
char *str = new char[10];
char **pstr = &str;

test(pstr);

return 0;
}

My error output is:

1>------ Build started: Project: test, Configuration: Debug Win32
1>Compiling...
1>test.cpp
1>test.cpp(3) : error C2065: 'cout' : undeclared identifier
1>test.cpp(3) : error C3861: 'str': identifier not found
1>test.cpp(11) : error C2664: 'test' : cannot convert parameter 1
from 'char **' to 'const char **'
1> Conversion loses qualifiers
1>Build log was saved at "file://xxxxxx\Debug\BuildLog.htm"
1>test - 3 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped

Any help would be appreciated. I'm sure someone must have brought this
issue up before, but it's not easy to search for, let's put it that way.

 

[James Aguilar]

Corrected code:

#include <iostream>
#include <string>

using namespace std;

void test(const char **p)
{
cout << string(*p) << '\n';
}

int main()
{
char *str = new char[10];
char **pstr = &str;

test(pstr);

return 0;
}

Sorry about that.

 

[Andrey Tarasevich]

Quick question. Why, in the following code sample, can I not convert a
char ** to a const char **?
...

See the FAQ

http://www.parashift.com/c++-faq-lite/const-correctness.html#faq-18.17

 

[Frederick Gotham]

James Aguilar posted:

Quick question. Why, in the following code sample, can I not convert a
char ** to a const char **?

Here's something that was posted not so long ago:

http://groups.google.ie/group/comp.std.c++/msg/8836b5949eb07061?hl=en&