Thread: C4267 conversion from 'size_t' to 'int'

Hello,

I am getting two instances of the warning C4267 in my function. This warning says: 'initializing' : conversion from 'size_t' to 'int', possible loss of data

I looked this up on the internet and it doesn't seem to be a great big deal, but I was wondering if there was a method I could use to rewrite the function so I can get a clean compile.

Code:

// This program will count the occurrences of a string within a string.
#include <iostream>  // cin, cout, <<, >>
#include <string>    // string
using namespace std;


int count;
int occurCount(string quote)
{
	
 cout << quote << endl;   // quote will come from a driver file

 int position = quote.find ("a spider", 0);   // warning C4267
	 if (position == string::npos)
	 count = 0;
	 else count = 1;
                        while (position != string::npos)
	 {
	 position = quote.find ("a spider", position + 1); //C4267
             
	 if (position > 0)
                 {
                 count++;				 
	 }			 			 
	 }
	 return count;
}

I am sorry about the indentation/spacing. It looks alot better in Visual Studio.

Simple, if it returns size_t, make position a size_t variable.

Code:

// This program will count the occurrences of a string within a string.
#include <iostream>  // cin, cout, <<, >>
#include <string>    // string
using namespace std;


int count;
int occurCount(string quote)
{
	
 cout << quote << endl;   // quote will come from a driver file

 size_t position = quote.find ("a spider", 0);   // warning C4267
	 if (position == string::npos)
	 count = 0;
	 else count = 1;
                        while (position != string::npos)
	 {
	 position = quote.find ("a spider", position + 1); //C4267
             
	 if (position > 0)
                 {
                 count++;				 
	 }			 			 
	 }
	 return count;
}

Gee, that was simple. Thanks!

>Simple, if it returns size_t, make position a size_t variable.
While that particular implementation may use size_t, it's better to use the correct type that the function returns. In this case, string::size_type.

Code:

string::size_type position = quote.find ("a spider", 0);

>While that particular implementation may use size_t, it's better >to use the correct type that the function returns. In this case, >string::size_type.

But would I still need to declare:

Code:

int position = quote.find ("a spider", 0);   // warning C4267

as a type size_t, rather than int? It compiles cleanly as long as I declare it as type size_t. I think what I want to ask is what does adding string::size_type do for the code? I will use it regardless, because it looks cool, but I surely do not understand what it does.

>I think what I want to ask is what does adding string::size_type do for the code?
It makes it more portable.

Thank you.

Originally posted by Prelude
>I think what I want to ask is what does adding string::size_type do for the code?
It makes it more portable.

Could you elaborate more on that portability issue? Are you saying that int will not compatible on some platform? or??

>Are you saying that int will not compatible on some platform?
No, I'm saying that the return type of string::find() may not return int or size_t. You don't know, so you should use string::size_type to be sure that you're using the right type.

Originally posted by Prelude
>Are you saying that int will not compatible on some platform?
No, I'm saying that the return type of string::find() may not return int or size_t. You don't know, so you should use string::size_type to be sure that you're using the right type.

Okay, I'm back and get even more confused. You say, "string::find() may not return int or size_t???????"
If I want to use string::find, do I not look it up and it tells me the function's arguments and what it returns as well as its return type ???
Or are you saying that string::find from ,say ,.NET's library may differ from that of g++ in their return type??
EDIT: wait a sec, size_type is not the same as size_t, huh. But size_type could be size_t and int??

>But size_type could be size_t and int??
It could be either. It could be something different. It's implementation defined.