How to initialize an integer pointer in C++?

I have a very simple question.

I want to write the开发者_如何学运维 below line of code in 2 lines :

IplImage *image = 0;

like :

IplImage *image;
image = 0;

I want to know what I have written is correct or else I want to know how to write the correct one (in two lines).

Thanks

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Perfectly correct. But if you don't have a very good reason to do it that way, I'd suggest leaving it as a single line that both declares and initializes it. It's more obvious, and you're less likely to ever miss initializing a pointer that way.

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It is correct. Why didn't you just try it?

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Writing

IplImage *image = 0;

seem to be clearer as it is obvious that a pointer is used.

With

IplImage *image;
image = 0;

you may have additional lines of code between the first and the second line. The second line (image = 0) appears less clear to me. Maybe renaming the variable to pImage improves readability if you prefer the second option (two liner).

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Iplimage is the structure defined in opencv. You can use code below to initialize the pointer:

Iplimage* image=cvCreateImage(width,height,channels);

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In C++

IplImage *image(NULL);

woul also be allowed, even if it may be confusing about your image to be allocated by calling the constructor with the first argument set to NULL.

However, declaring + initializing in 1 line is still remended and almost all case. The only case I see where it's better to initilize in 2 lines it's when the line is too long.