pointer passing between functions fails with error

Question

I am trying to write two functions, one calls the other and passes in an argument:

int RegisterImage( const char * streamID, IMGStream & c ) {
...
}

int OpenImage( const char * streamid, int dsize ) {
ImageStream * im;
int idx = -1;

if ( GetImgRegIdx(streamid, dsize, im) )
          idx = RegisterImage (streamid, im);
return idx;
}

The calling of "RegisterImage()" fails. It complains about: "in passing argument 2 of ‘int Core::RegisterImage(const char*, IMGStream&)’"

Can anybody help me understand why it's complaining, and how to fix it? Thanks so much

What's the relationship between IMGStream and ImageStream? — timrau
– timrau, Commented Dec 10, 2013 at 1:21

ScarletAmaranth · Accepted Answer · 2013-12-10 01:21:17Z

1

ImageStream * im; is a pointer, your RegisterIMage() expects a reference as its second argument. You need to pass in *im. References implicitly refer to objects, not to addresses. Your ImageStream* is type that holds an address.

answered Dec 10, 2013 at 1:21

ScarletAmaranth

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splrs · Accepted Answer · 2013-12-10 01:26:45Z

0

Assuming IMGStream and ImageStream objects are the same type (one being a typedef of the other or something), then the function is expecting a reference and you're passing a pointer.

So, if IMGStream and ImageStream objects are actually the same type, you should pass *im instead of im.

answered Dec 10, 2013 at 1:26

splrs

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Comments

Michael · Accepted Answer · 2013-12-10 01:24:35Z

0

It's asking for an IMGStream& which you read as 'IMGStream Reference'. Although this acts very much like passing a pointer, the syntax must not be.

Try de-referencing your pointer with a * (the de-reference operator)

     idx = RegisterImage (streamid, *im);

answered Dec 10, 2013 at 1:24

Michael

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