what is meaning of bus error in compattive programming

C++
 Bus Error (also known as SIGBUS and is usually signal 10) 
 occur when a process is trying to access memory that the CPU 
 cannot physically address.In other words the memory tried to 
 access by the program is not a valid memory address.
 It caused due to alignment issues with the CPU 
 (eg. trying to read a long from an address which isn’t a multiple of 4). SIGBUS is abbrivation for “Bus Error”.
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