1. Agenda Make Utility Command Line Arguments in Unix
Individual Assignment – 8-Puzzle

2. Separate Compilation using ‘make’
Two processes occur when we compile a program:
1) Source code is compiled into an object file.
2) Object file is linked to form a load module or executable file.

3. Compilation g++ -Wall -c myfile.cc
2) Translates source code into machine readable code.
3) References to externally defined functions and/or variables are incomplete.

4. Linking g++ -o myfile myfile.o
Resolves external references left hanging at compilation time.
Creates a monolithic executable file.

5. Separate Compilation This is the process of –
1) Compiling a set of object files, individually. (multiple steps)
2) Then, linking those object files into an executable file. (one step)

6. Need of Separate Compilation
When working on a substantial programming project, we want to use separate compilation because:
1) Entire program not compiled after only one small change, i.e. faster.
2) Team members can compile parts of a program (obj files) to be collected and linked later.
3) The "make" program will "make" life easy!!! (once its set up)

7. Sample Makefile CC = g++ BFILES = insertion.o insertionf.o
insertion : $(BFILES)
$(CC) -o insertion $(BFILES)
insertion.o: insertion.cpp insertion.h
$(CC) -c insertion.cpp

8. Sample Makefile […contd]
insertionf.o: insertionf.cpp insertion.h
$(CC) -c insertionf.cpp
clean:
rm *.o
rm insertion

9. Terms and Definitions CC = g++  Macro Definition
BFILES = insertion.o insertionf.o  Macro Definition
insertion : $(BFILES)  Macro Expansion
$(CC) -o insertion $(BFILES)  Macro Definition
insertion.o: insertion.cpp insertion.h
$(CC) -c insertion.cpp  Macro Definition

10. Command Line Arguments in Unix/C++
Say you have a program to calculate the average of input values. (avgPrgm)
It looks better to invoke the program as follows
$ avgPrgm ……
rather than asking the user to first enter the number of values that he/she wants to find the average of.

11. Use of argv and argc A program that does:
A program that does not allow the use of command line arguments:
Main() {
//Statements }
A program that does:
Main(int argc, char* argv[])

12. Use of argv and argc [….Contd]
argc: a count of number of arguments provided on the command line.
argv[]: a vector (array) of pointers to char (strings) representing the command line elements.

13. Use of argv and argc [Example]
Suppose main is the main program in command.cc and it is compiled and run with the following:
38%g++ command.cc –o command
39%command foo bar baz

14. Eaxmple […contd]
…..then when main begins argv and argc are as follows: 4
argc
argv f o \0 c m a n d b r

15. An Example Using argv and argc
//Demonstrate the use of argv and argc
# include <iostream.h>
main(int argc, char *argv[]) {
int i;
cout<<“The number of elements on the command line:” <<argc<<endl;
cout<<“The name of the program:<<argv[0]<<endl;
for (i=1; i<argc; i++)
cout<<“Command line argument number”<<i<<“:”<<arg[i]<<endl; }

16. Eaxmple […contd] 38% g++ cmdline.cc –o cmdline 39% cmdline foo bar baz
The number of elements on command line:4
The name of the program:cmdline
Command line argument number1:foo
Command line argument number2:bar
Command line argument number3:baz
40%

17. An Equivalent Usage Since: 1) argv[] is of type char*
2) and since arrays in C/C++ are pointers, then:
argv is of type char **
Therefore,
void main::process(int argc, char *argv[])
is equivalent to
void main::process(int argc, char **argv)
Note that following is an optimization:
void main::process(int argc, const char **argv)