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Hi

any idea why I am getting something like


main.cpp:177: error: invalid operands of types ‘const char [11]’ and ‘const char [8]’ to binary ‘operator+’


when trying to compile something like

int main(int argc, char* argv[])
{
string a = ".........." + ".......";
cout << a << endl;
}

how can I solve this, I have few lines and use + to concatenate them
together.

thanks

Gary Wessle wrote:
> Hi
>
> any idea why I am getting something like
>
>
> main.cpp:177: error: invalid operands of types 'const char [11]' and 'const char [8]' to binary 'operator+'
>
>
> when trying to compile something like
>
> int main(int argc, char* argv[])
> {
> string a = ".........." + ".......";
> cout << a << endl;
> }
>
> how can I solve this, I have few lines and use + to concatenate them
> together.
>
> thanks

You think the above is concatinating literal strings but its actually
attempting to add their pointers. Which is not allowed (obviously) when
constructing the std::string.

try:
std::string a = "..........";
a += ".......";

or better:

std::string sline1(10, '.');
std::string sline2(5, '.');
std::cout << sline1 << " title " << sline2 << std::endl;

Gary Wessle wrote:
> Hi
>
> any idea why I am getting something like
>
>
> main.cpp:177: error: invalid operands of types ‘const char [11]’ and ‘const char [8]’ to binary ‘operator+’
>
>
> when trying to compile something like
>
> int main(int argc, char* argv[])
> {
> string a = ".........." + ".......";

string a = string("..........") + ".......";
> cout << a << endl;
> }
>
> how can I solve this, I have few lines and use + to concatenate them
> together.

There is no :

string operator+( const char *, const char * )

Gary Wessle wrote:

> Hi
>
> any idea why I am getting something like
>
>
> main.cpp:177: error: invalid operands of types ‘const char [11]’
> and ‘const char [8]’ to binary ‘operator+’
>
>
> when trying to compile something like
>
> int main(int argc, char* argv[])
> {
> string a = ".........." + ".......";
> cout << a << endl;
> }

There's not a std::string operator + that take two char pointers.

> how can I solve this, I have few lines and use + to concatenate them
> together.

std::string a = ".......";
a += ".....";



Brian

"Gary Wessle" <> wrote in message
news:...
> Hi
>
> any idea why I am getting something like
>
>
> main.cpp:177: error: invalid operands of types 'const char [11]' and
> 'const char [8]' to binary 'operator+'
>
>
> when trying to compile something like
>
> int main(int argc, char* argv[])
> {
> string a = ".........." + ".......";
> cout << a << endl;
> }
>
> how can I solve this, I have few lines and use + to concatenate them
> together.
>
> thanks

As explained, you are actually trying to add two char pointers. A few ways
around:

std::string a = "......";
a += ".....";

or

std::string a = std::string("...........") + "............";

On 16 Dec 2006 16:54:40 +1100, Gary Wessle <> wrote in
comp.lang.c++:

> Hi
>
> any idea why I am getting something like
>
>
> main.cpp:177: error: invalid operands of types ‘const char [11]’ and ‘const char [8]’ to binary ‘operator+’
>
>
> when trying to compile something like
>
> int main(int argc, char* argv[])
> {
> string a = ".........." + ".......";
> cout << a << endl;
> }
>
> how can I solve this, I have few lines and use + to concatenate them
> together.

In addition to Gianni's answer, there is one thing you can do that
only works for string literals in source code, namely leave out the
'+'.

The code:

string a = "abc" "def" "ghi";

....produces exactly the same result as:

string a = "abcdefghi";

And so does this:

string a = "abc"
"def"

"ghi";

String literals that are separated by nothing but white space are
concatenated by the preprocessor when compiling.

--
Jack Klein
Home: http://JK-Technology.Com
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