get_string

Finds the field corresponding to fieldname, and returns the string contained in the field's value.

Caller is responsible for making sure the field exists and has the correct type.

The string should not be modified, and remains valid until the next call to a gst_structure_*() function with the given structure.

Parameters:

this	a Structure
fieldname	the name of a field

Returns:

a pointer to the string or null when the field did not exist or did not contain a string.