CODEWITHSUNDEEP
c++variadic-functions
will
will

Reputation: 1407

C++ - va_list Bad Pointer

I am getting an exception of a bad pointer (0xcccccccc ) for temp below under case 's':

string Logger::format(const char *str, va_list args)
{
    ostringstream output;

    for(int i = 0; i < strlen(str); ++i)
    {
        if(str[i] == '%' && str[i+1] != '%' && i+1 < strlen(str))
        {
            switch(str[i+1])
            {
            case 's':
            {
                char *temp = va_arg(args, char*);
                output << temp;
                break;
            }
            case 'i':
            {
                int temp = va_arg(args, int);
                output << temp;
                break;
            }
            case 'd':
            {
                double temp = va_arg(args, double);
                output << temp;
                break;
            }
            case 'f':
            {
                float temp = va_arg(args, float);
                output << temp;
                break;
            }
            default:
                output << str[i];
            }

            i++;
        }
        else
        {
            output << str[i];
        }
    }

    return output.str();
}

The above function is called by this:

void Logger::debugFormat(string message, ...)
{
    const char* cstr = message.c_str();

    va_list args;
    va_start(args, cstr);

    record(DEBUGGING, format(cstr, args));

    va_end(args);
}

I am calling the above this way in all my code

Logger::debugFormat("Loading Image %s", path.c_str());

Any other type (int, double, float) work all fine. Any help is appreciated.

Upvotes: 1

Views: 1097

Answers (1)

jamesdlin
jamesdlin

Reputation: 90175

You aren't using va_start properly. The second argument is supposed to be the function parameter after which the variable list of arguments (represented by ...) starts. That is, it should be:

va_start(args, message);

Upvotes: 4

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