String + int (overloading)

Hi!

I want to overload operator +, so I can write strings in this way => String s = "Age: " + 20; // int, long and double

How am I supposed to do that?

Here is some code that may be educational:

Code:

---

class thing {
    thing(char * str) {
          /* do stuff*/
    };
};

struct memptr {
    void * operator =(void * val) {
          value = val;
          return value;
    };
};
/*...later...*/
    // memptr obj = new thing("HELLO");
    // the above line does not work; the two lines below do
    memptr obj;
    obj = new thing("HELLO");

---

Don't ask me why. Maybe it will help you, though.

String operator+(int) is already overloaded...

don't do math with strings

All I want to do is this =>

Code:

---

int cal = 200
String s = "Result is " + calc;

---

And this code must produce a string which looks like this=> s = "Result is 200". I want to create java-like String class. That's it.

So if anyone has any good suggestion how can I add numbers to string than please tell me, otherwise don't reply at all.

Better create a general numeric-to-string conversion template, then catenate the strings with standard operator+.

I don't want to use templates. I want to overload.

This shows how to convert a number to a string the rest you should be able to figure out.
http://faq.cprogramming.com/cgi-bin/...&id=1043284385

Ok this works! Thanks.

But what about overloading this =>

int cal = 200;
char *text = "Result is " + calc;

How can I overload this?

A very brief search on Google tuend up this which should be rather helpful.

Quote:

---

Originally Posted by GaPe

Ok this works! Thanks.

But what about overloading this =>

int cal = 200;
char *text = "Result is " + calc;

How can I overload this?

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You can't overload that example because at least one parameter from a operator function must be a class. You have 2 primitive types (char* and int), it doens't work. If you could, someone would have fun overloading 'int operator+(int,int);' :D
Yet you can do

Code:

---

int cal = 200;
std::string text = "Result is ";
text = text + calc;
//or
text += calc;

---

I use MS VC++ 6, and std::string + int operator is ambigous - buggy libs. So have overloaded it. First you try something...
If this helps: print the number to a string, then concatnate it with the other string.

Code:

---

#include <iostream>
#include <string>
#include <sstream>

std::string operator+ (const std::string& s, int i)
{
        std::ostringstream os;
        os << i;
        return s + os.str();
}

int main()
{
        using namespace std;
        string s = string("The result is: ") + 200;
        cout<<s<<endl;
}

---

Funny thing about:

Code:

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int cal = 200;
char *text = "Result is " + calc;

---

is that "Result is " is really just a const char* so by adding calc to it you are getting some memory you probably shouldn't be touching