CODEWITHSUNDEEP
c++c++11templates
John Code
John Code

Reputation: 675

Template function not recognised

I'm trying to write a set of functions which converts strings to their corresponding numeric value, "int, float, double..." but My templated function is not recognized by the c++ compiler.
When I call it, I get a message stating "No matching Function for call. I was returning a function of type T from this function, but I had this error message, I've tried modifying the function so it could change the value of a variable passed by reference, but the error persists.
I've tried modifying this function but it t doesnt still works please help. I have several versions of this function which are overriden, as follows:

static void convertValue(eOperandType type, const std::string &value, FloatOperandType typeDeterminer, T &container)
    {
        try
        {
            container = std::stof(value);
        }
        catch (std::invalid_argument e)
        {
            throw AVMException("The value passed as number is not valid");
        }
        catch (std::out_of_range e)
        {
            char *msg = "The value passed is out of the range of the typed passed";
            throw AVMException(msg);
        }
        catch (exception& e)
        {
            throw AVMException("An unexpected error occured when converting value types");
        }
    }
template <typename T>
    static void convertValue(eOperandType type, const std::string &value, IntOperandType typeDeterminer, T &container)
    {
        int val = 0;

        try
        {
            val = std::stoi(value);
            switch(type)
            {
                case eOperandType::Int8:
                    if(val < -128 || val > 127)
                        throw AVMWarnException("Overflow for type Int8");
                case eOperandType::Int16:
                    if(val < -32768 || val > 32,767)
                        throw AVMWarnException("Overflow for type Int16");
                case eOperandType::Int32:
                    if(val < -2147483648 || val > 2147483647)
                        throw AVMWarnException("Overflow for type Int32");
            }

            container = std::stoi(value);
        }
        catch (std::invalid_argument e)
        {
            throw AVMException("The value passed as number is not valid");
        }
        catch (std::out_of_range e)
        {
            char *msg = "The value passed is out of the range of the typed passed";
            throw AVMException(msg);
        }
        catch (exception& e)
        {
            throw AVMException("An unexpected error occured when converting value types");
        }
    }

Here is how I call the function:

 int v = 0;
 Converter::convertValue<int>("20", eOperandType::Int8, IntOperandType::_Int8, &v);

Upvotes: 3

Views: 709

Answers (2)

alter_igel
alter_igel

Reputation: 7202

If I may hazard a guess that eOperandType is an enum type, then it makes sense that you can't convert "20" to it. Additionally, you pass an int* where an int& is expected. Notice your function's signature:

template <typename T>
void convertValue(eOperandType, const std::string&, IntOperandType, T&)

and compare this to how you call the function:

convertValue<int>("20", eOperandType::Int8, IntOperandType::_Int8, &v);

Here, your parameters have the following types:

const char[3], eOperandType, IntOperandType, int*

Notice the mismatch from the signature? You probably want to call it like this:

int v = 0;
Converter::convertValue<int>(eOperandType::Int8, "20", IntOperandType::_Int8, v);

where "20" is implicitly convertible to const std::string& and v, which is an lvalue of type int, can be implicitly bound to an lvalue reference to int, int&.

Upvotes: 2

Stuckatmarine
Stuckatmarine

Reputation: 62

It could be the string coming before the e operand type when you call the function, the param lists do not match.

Upvotes: 0

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