double concatenation with string

I'm having trouble concatenating a string with a double. It should work fine but it doesn't:

Code:

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temp_equ = ( temp_ans + temp_equ.substr( op_indices[counter]+1 ) );

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temp_equ is a string.. (a c++ string)

temp_ans is a double.


The weird thing is I created a test project and the following worked fine:

Code:

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string s = 3.0 + "asdf";

and

double x = 3;
string s = x + "asdf";

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Which is virtually what I'm trying to do.


In my real project I tried the following to make sure it wasn't something to do with the substring:

Code:

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temp_equ =  temp_ans + "asdf";

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and I still get the following exception:

Code:

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67 C:\Dev-Cpp\Projects\Equation Parser\main.cpp invalid operands of types `double' and `const char[5]' to binary `operator+'

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What exactly am I doing wrong? It works in another file doing the exact same thing, but not in another...

I don't think the string class' + operator is overloaded like that. You'll need to convert the double to a string in another way, using a stringstream, sscanf, boost::lexical_cast, etc...

Perfect. Thanks sunburnt.