7.2 Exercise 7.2

The following functions invoked in alloc_and_init() raise the following exception types if they should fail:

allocate_array() noMem 


sort_array()     int 


register_data()  string 

Insert one or more try blocks and associated catch clauses where appropriate to handle these exceptions. Simply print the occurrence of the error within the catch clause.

Rather than surround each individual function invocation with a separate try block, I have chosen to surround the entire set of calls with a single try block that contains three associated catch clauses:

int *alloc_and_init( string file_name ) 


{ 


   ifstream infile( file_name.c_str() ); 


   if ( ! infile )return 0; 





   int elem_cnt; 


   infile >> elem_cnt; 


   if ( ! infile ) return 0; 





   try { 


      int *pi = allocate_array( elem_cnt ); 


      int elem; 


      int index = 0; 


      while ( infile >> elem && index < elem_cnt ) 


              pi[ index++ ] = elem; 





      sort_array( pi, elem_cnt ); 


      register_data( pi ); 


   } 


   catch( const noMem &memFail ) { 


         cerr << "alloc_and_init(): allocate_array failure!\n" 


              << memFail.what() << endl; 


         return 0; 


   } 


   catch( int &sortFail ) { 


         cerr << "alloc_and_init(): sort_array failure!\n" 


              << "thrown integer value: " << sortFail << endl; 


         return 0; 


   } 


   catch( string &registerFail ) { 


         cerr << "alloc_and_init(): register_data failure!\n" 


              << "thrown string value: " 


               << registerFail << endl; 


         return 0; 


   } 


   return pi; // reach here only if no throw occurred ... 


}