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Assignment 1 Debrief

Assignment 1 Debrief. Andy Wang Data Structures, Algorithms, and Generic Programming. makefile. Reasons for using a makefile: Standard practice in the UNIX world Describe dependencies among files Easy to rename files, change include paths, and so on…

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Assignment 1 Debrief

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  1. Assignment 1 Debrief Andy Wang Data Structures, Algorithms, and Generic Programming

  2. makefile • Reasons for using a makefile: • Standard practice in the UNIX world • Describe dependencies among files • Easy to rename files, change include paths, and so on… • Automatically generate header file dependencies

  3. A Simplemakefile all: libbit.a sieve.x libbit.a: bitvector.o ar cr libbit.a bitvector.o ranlib libbit.o sieve.x: main.o sieve.o libbit.a g++ -g –ansi –Wall main.o sieve.o –I/usr/include –L. –lbit –o sieve.x bitvector.o: bitvector.cpp bitvector.h g++ -g –ansi –Wall –I/usr/include –c –o bitvector.o bitvector.cpp sieve.o: sieve.cpp bitvector.h sieve.h g++ -g –ansi –Wall –I/usr/include –c –o sieve.o sieve.cpp main.o: main.cpp sieve.h g++ -g –ansi –Wall –I/usr/include –c –o main.o main.cpp clean: rm –f *.o libbit.a sieve.x core *~ *.bak

  4. To ease changing flags FLAGS = -g –ansi –Wall -O all: libbit.a sieve.x libbit.a: bitvector.o ar cr libbit.a bitvector.o ranlib libbit.o sieve.x: main.o sieve.o libbit.a g++ $(FLAGS) main.o sieve.o –I/usr/include –L. –lbit –o sieve.x bitvector.o: bitvector.cpp bitvector.h g++ $(FLAGS) –I/usr/include –c –o bitvector.o bitvector.cpp sieve.o: sieve.cpp bitvector.h sieve.h g++ $(FLAGS) –I/usr/include –c –o sieve.o sieve.cpp main.o: main.cpp sieve.h g++ $(FLAGS) –I/usr/include –c –o main.o main.cpp clean: rm –f *.o libbit.a sieve.x core *~ *.bak

  5. make depend FLAGS = -g –ansi –Wall -O all: libbit.a sieve.x libbit.a: bitvector.o ar cr libbit.a bitvector.o ranlib libbit.o sieve.x: main.o sieve.o libbit.a g++ $(FLAGS) main.o sieve.o –I/usr/include –L. –lbit –o sieve.x bitvector.o: bitvector.cpp bitvector.h g++ $(FLAGS) –I/usr/include –c –o bitvector.o bitvector.cpp sieve.o: sieve.cpp bitvector.h sieve.h g++ $(FLAGS) –I/usr/include –c –o sieve.o sieve.cpp main.o: main.cpp sieve.h g++ $(FLAGS) –I/usr/include –c –o main.o main.cpp clean: rm –f *.o libbit.a sieve.x core *~ *.bak depend: makedepend -- $(FLAGS) –I/usr/include bitvector.cpp \ sieve.cpp main.cpp bitvector.h sieve.h # DO NOT DELETE THIS LINE – makedepend depends on it.

  6. Systematic Conversion FLAGS = -g –ansi –Wall -O all: libbit.a sieve.x libbit.a: bitvector.o ar cr libbit.a bitvector.o ranlib libbit.o sieve.x: main.o sieve.o libbit.a g++ $(FLAGS) main.o sieve.o –I/usr/include –L. –lbit –o sieve.x .cpp.o: g++ $(FLAGS) –I/usr/include –c –o $*.o $*.cpp clean: rm –f *.o libbit.a sieve.x core *~ *.bak depend: makedepend -- $(FLAGS) –I/usr/include bitvector.cpp \ sieve.cpp main.cpp bitvector.h sieve.h # DO NOT DELETE THIS LINE – makedepend depends on it.

  7. To ease changing include paths INC = -I/usr/include FLAGS = -g –ansi –Wall -O all: libbit.a sieve.x libbit.a: bitvector.o ar cr libbit.a bitvector.o ranlib libbit.o sieve.x: main.o sieve.o libbit.a g++ $(FLAGS) main.o sieve.o $(INC) –L. –lbit –o sieve.x .cpp.o: g++ $(FLAGS) $(INC) –c –o $*.o $*.cpp clean: rm –f *.o libbit.a sieve.x core *~ *.bak depend: makedepend -- $(FLAGS) $(INC) bitvector.cpp sieve.cpp main.cpp \ bitvector.h sieve.h # DO NOT DELETE THIS LINE – makedepend depends on it.

  8. BitVector 23…….16 15………8 7………0 unsigned char array array[2] array[1] array[0] ByteNumber(17) = 2 Mask(17) = 00000010(2)

  9. ByteNumber(bit_index) • Bad name • Should be BasictypeArrayIndexNumber() • Goal: • Return the index of the Basictype array that holds the bit

  10. Set() • Goal: • 10100…010010  1111…..11111 • Array[j] = 0x01; // use only 1 out of n bits • Array[j] |= 0xFF; // OK only for unsigned char • Array[j] |= 0xFFFFFFFF; • Array[j] |= ~0x0;

  11. Set(bit_index) • Goal: • 10100…010010  10110…010010 • To set a bit to 1 • 0 | 1  1 • 1 | 1  1 • To preserve remaining bits: • 0 | 0  0 • 1 | 0  1

  12. Set(bit_index) 10100…010010 | 00010…000000 10110…010010 Array[ByteNumber(bit_index)] |= Mask(bit_index);

  13. Unset() • Goal: • 10100…010010  00000….000000 • 0 & 0 = 0 • 1 & 0 = 0 • Array[j] &= 0x0; • 0 ^ 0 = 0 • 1 ^ 1 = 0 • Array[j] = Array[j] ^ Array[j];

  14. A Neat Trick • A = 11001010 • B = 00100101 • A = A ^ B • B = A ^ B • A = A ^ B

  15. Unset(bit_index) • Goal: • 10100…010010  10000…010010 • To set a bit to 0: • 0 & 0  0 • 1 & 0  0 • To preserve remaining bits: • 0 & 1  0 • 1 & 1  1

  16. Unset(bit_index) 10100…010010 & 11011…111111 10000…010010 Array[ByteNumber(bit_index)] &= ~Mask(bit_index);

  17. Flip() • Goal: • 10100…010010  01011….101101 • ~1 = 0 • ~0 = 1 • Array[j] = ~Array[j]; • 1 ^ 1 = 0 • 0 ^ 1 = 1 • Array[j] = Array[j] ^ ~0x0;

  18. Flip(bit_index) • Goal: • 10100…010010  10101…010010 if (Test(bit_number)) { Unset(bit_number); } else { Set(bit_number); }

  19. Common Errors • Basictype vector vs. bit vector • != vs. |= • == vs. = • Mask() vs. BitVector::Mask() • #include <bitvector.h> vs. #include “bitvector.h”

  20. Common Errors Foo(); { } vs. Foo() { } Personally, I prefer… Foo() { }

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