how to pass in a pointer to a pointer

This is a discussion on how to pass in a pointer to a pointer within the C Programming forums, part of the General Programming Boards category; Code: // sock_create signature ... int sock_create(int family, int type, int protocol, struct socket **res); struct bam { union am ...

  1. #1
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    Feb 2011
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    how to pass in a pointer to a pointer

    Code:
    // sock_create signature ... 
    int sock_create(int family, int type, int protocol, struct socket **res);
    
    struct bam {
        union am *lay;
    };
    
    struct cam {
        struct socket *skt; 
    };
    How do I pass in the skt member of 'struct cam' to function sock_create() which has arg that requires a pointer to a pointer?

    Code:
    	struct bam *bm;
    	struct cam *cm;
    
    	// ...
    
            cm = (struct cam *)bm->lay;
            
    	// cm->skt wrong here, but not sure how to pass in.
            ret = sock_create(AF_INET, SOCK_STREAM, IPPROTO_TCP, cm->skt);

  2. #2
    C++ Witch laserlight's Avatar
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    Take the address of the pointer
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  3. #3
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    Quote Originally Posted by laserlight View Post
    Take the address of the pointer
    I understand that's what I need to do, but confused on the syntax ... &(cm->skt)

  4. #4
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    Yep, though you don't need the parentheses.
    It is too clear and so it is hard to see.
    A dunce once searched for fire with a lighted lantern.
    Had he known what fire was,
    He could have cooked his rice much sooner.

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