Dereferencing pointer to incomplete type

presentfile :/usr/include/asterisk/channel.h
in my func i want to use below …

struct ast_channel_iterator *iter = NULL;
struct ast_channel *c=NULL;
char copy_myappl[40];
size_t copy_appl_size = sizeof(copy_myappl);

                            for (; (c = ast_channel_iterator_next(iter)); ast_channel_unref(c))

	snprintf(copy_myappl, sizeof(copy_myappl), "%s", c->appl );


error: dereferencing pointer to incomplete type at this line snprintf(copy_myappl, sizeof(copy_myappl), “%s”, c->appl );

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The latest versions of Asterisk hide the structure of channels and you must use the provided methods/properties to access their fields.

Solved . by using ast_channel_appl© and ast_channel_data(c