c - Cannot pass a variable of my own (non-standard) type to a function -

i'm writing program must normalize audio *.wav file. there task "to display header's data": chunkid, chunksize , on.

i want make function named display_hdr (in order have less code in main.c file, become esier read code). have pass function header's variable (variable of type header) argument, writes

functions.h|1|error: unknown type name 'header'| 

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main.c:

typedef struct fmt {     char        subchunk1id[4];     int         subchunk1size;     short int   audioformat;     short int   numchannels;     int         samplerate;     int         byterate;     short int   blockalign;     short int   bitspersample; } fmt;  typedef struct data {     char        subchunk2id[4];     int         subchunk2size;     int         data[]; } data;  typedef struct header {     char        chunkid[4];     int         chunksize;     char        format[4];     fmt         s1;     data        s2; } header; 

header's variable declared in way:

header hdr; 

and now, when try pass hdr function prints error:

functions.h|1|error: unknown type name 'header'| 

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functions.h

void display_hdr( header hdr ) {     printf("\n*********************************\n");     printf("wave file's metadata:\n\n");      printf("%4.4s\n",  hdr.chunkid   );     printf("%d\n",     hdr.chunksize );     printf("%4.4s\n",  hdr.format    );      printf("%4.4s\n",  hdr.s1.subchunk1id   );     printf("%d\n",     hdr.s1.subchunk1size );     printf("%d\n",     hdr.s1.audioformat   );     printf("%d\n",     hdr.s1.numchannels   );     printf("%d\n",     hdr.s1.samplerate    );     printf("%d\n",     hdr.s1.byterate      );     printf("%d\n",     hdr.s1.blockalign    );     printf("%d\n",     hdr.s1.bitspersample );      printf("%4.4s\n",  hdr.s2.subchunk2id   );     printf("%d\n",     hdr.s2.subchunk2size );   /// samples' size     printf("\n*********************************\n");     return; } 

so, how pass variable of own (non-standard) type function argument?

"the scope of global variables can restricted placing declaration. visible declaration until end of current source file."

there no problem on subject ( no warning or error ). moved definition of struct (type) main.c function.c (where variable header of type hdr declared).

function.h

typedef struct fmt {     char        subchunk1id[4];     int         subchunk1size;     short int   audioformat;     short int   numchannels;     int         samplerate;     int         byterate;     short int   blockalign;     short int   bitspersample; } fmt;  typedef struct data {     char        subchunk2id[4];     int         subchunk2size;     int         data[]; } data;  typedef struct header {     char        chunkid[4];     int         chunksize;     char        format[4];     fmt         s1;     data        s2; } header;     /* `header` type created. */  header hdr;   /* after `header`type created. */  void display_hdr( header hdr ) {     printf("\n*********************************\n");     printf("wave file's metadata:\n\n");      printf("%4.4s\n",  hdr.chunkid   );     printf("%d\n",     hdr.chunksize );     printf("%4.4s\n",  hdr.format    );      printf("%4.4s\n",  hdr.s1.subchunk1id   );     printf("%d\n",     hdr.s1.subchunk1size );     printf("%d\n",     hdr.s1.audioformat   );     printf("%d\n",     hdr.s1.numchannels   );     printf("%d\n",     hdr.s1.samplerate    );     printf("%d\n",     hdr.s1.byterate      );     printf("%d\n",     hdr.s1.blockalign    );     printf("%d\n",     hdr.s1.bitspersample );      printf("%4.4s\n",  hdr.s2.subchunk2id   );     printf("%d\n",     hdr.s2.subchunk2size );   /// samples' size     printf("\n*********************************\n");     return; } 

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ps

of course pass pointer function, i'd pass variable. there no need thought better (economy of memory).

the problem because of misunderstanding (poor/bad understanding) of 'scope' properly.

pss

maybe, andrew w's right in way, doesn't solve current problem. quite type of problem. worth reading too!