How to use assert?

I have this method:

Code:

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void setvisible(Cell * C, int val)

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and i am asked to use assert to check that val is between 1 and 9 inclusive.

I wrote

Code:

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assert( (val >= '1') && (val <= '9') );

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Can someone please let me know if this is right, and if so what it actually does.

Thanks

that looks right -- but beweare because assert does nothing at all when the program is compiled for release mode.

And you need <assert.h>.

Quote:

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assert does nothing at all when the program is compiled for release mode.

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Or, rather, when NDEBUG is defined.