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lect02

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Code from lecture:

https://github.com/ucsb-cs24-mirza-s21/cs24-s21-lectures/tree/main/lect02

Topics

Structure of a program in memory

• Memory regions: Code (text), static, heap, stack

C++ References

• Creating aliases with references

Pointers

• Pointer declaration - difference/similarities with declaring basic types
• Accessing variables “indirectly” via pointers
• The address and indirection operators: “&” and “*”
• Differences between references and pointers
• Constant pointers and references, when and why to use them
• Pointers and arrays - similarities and differences
• Passing arrays to functions - specifically looking at how arrays degenerate to pointers on function calls.

Pointers: why do we need them?

• Pointers allow arrays to be passed to functions efficiently
• Pointers allow arrays of large structs to be traversed effiently

Pointer pitfalls

• Pointers can only point to one type of data (not generic)
• They don’t automatically point - need to do some work
• Bugs in code that involves pointers can cause your program to irrecoverably crash (Segmentation fault)
• Examples: dereferencing a null pointer, out of bound array access, dereferncing a pointer that has junk value.

Call by value, address and reference

• Understanding the differences via stack diagrams
• When and why to use each of these