Notes:

To run main.c while linking to main.h

gcc main.c _putchar.c //function name from main.h

Segmentation fault Causes

• Attempting to access a nonexistent memory address (outside process's address space)
• Attempting to access memory the program does not have rights to (such as kernel structures in process context)
• Attempting to write read-only memory (such as code segment)
• These in turn are often caused by programming errors that result in invalid memory access:
  • Dereferencing a null pointer, which usually points to an address that's not part of the process's address space
  • Dereferencing or assigning to an uninitialized pointer (wild pointer, which points to a random memory address)
  • Dereferencing or assigning to a freed pointer (dangling pointer, which points to memory that has been freed/deallocated/deleted)
  • A buffer overflow
  • A stack overflow
  • Attempting to execute a program that does not compile correctly. (Some compilers[which?] will output an executable file despite the presence of compile-time errors.)