C++ replacing part of string with a variable double

this program uses the string prompt and replaces "{0}" with 5.651 and "{1}" with 3.427 and it works fine. when i change the string to "{0:c}" and "{1:c}" to replace the substring and format them as currency, "{0:f}" and "{1:f}" to replace the substring and format them as fixed point notation, "{0:e}" and "{1:e}" to replace the substring and format them as scientific notation, "{0:i}" and "{1:i}" to replace the substring and round to an integer, they all work independently. but when i try and put them into cases like if("{0}"), else if("{0:c}") it only works if i am looking for "{0}" anything else it doesnt work. I get a debug error. How do i fix this, what am i doing wrong? thanks in advance.

void main()
{
    write("The number {0} is greater than {1}.\n", 5.651, 3.427);
}

void write(string prompt, ...)
{
    double small, large, temp;

    va_list arguments;
    va_start(arguments, prompt);

    large = va_arg(arguments, double);
    small = va_arg(arguments, double);
    if(small > large)
    {
        temp = large;
        large = small;
        small = temp;
    }

    if(prompt.find("{0}"))
    {
        ostringstream a;
        a << large;
        string arg1 = a.str();
        ostringstream s;
        s << small;
        string arg2 = s.str();

        size_t pos = prompt.find("{0}");
        prompt = prompt.replace(pos, 3, arg1);
        size_t pos2 = prompt.find("{1}");
        prompt = prompt.replace(pos2, 3, arg2);
    }

    else if(prompt.find("{0:c}") != string::npos)
    { 
        ostringstream a;
        a << large;
        string arg1 = "$" + a.str();
        ostringstream s;
        s << small;
        string arg2 = "$" + s.str();

        size_t pos = prompt.find("{0:c}");
        prompt = prompt.replace(pos, 3, arg1);
        size_t pos2 = prompt.find("{1:c}");
        prompt = prompt.replace(pos2, 3, arg2);
    }

    else if(prompt.find("{0:e}"))
    { 
        ostringstream a;
        a << scientific << large;
        string arg1 = a.str();
        ostringstream s;
        s << scientific << small;
        string arg2 = s.str();

        size_t pos = prompt.find("{0:e}");
        prompt = prompt.replace(pos, 3, arg1);
        size_t pos2 = prompt.find("{1:e}");
        prompt = prompt.replace(pos2, 3, arg2);
    }

    else if(prompt.find("{0:f}"))
    { 
        ostringstream a;
        a << fixed << setprecision(6) << large;
        string arg1 = a.str();
        ostringstream s;
        s << fixed << setprecision(6) << small;
        string arg2 = s.str();

       size_t pos = prompt.find("{0:f}");
       prompt = prompt.replace(pos, 3, arg1);
       size_t pos2 = prompt.find("{1:f}");
       prompt = prompt.replace(pos2, 3, arg2);
    }

    else if(prompt.find("{0:i}"))
    { 
        ostringstream a;
        a << (int)large;
        string arg1 = a.str();
        ostringstream s;
        s << (int)small;
        string arg2 = s.str();

        size_t pos = prompt.find("{0:i}");
        prompt = prompt.replace(pos, 3, arg1);
        size_t pos2 = prompt.find("{1:i}");
        prompt = prompt.replace(pos2, 3, arg2);
    }

    cout << prompt;
    cout << endl;

    va_end(arguments);
}