{"id":386,"date":"2019-05-22T03:06:54","date_gmt":"2019-05-22T03:06:54","guid":{"rendered":"http:\/\/sites.rutgers.edu\/demetrios-lambropoulos\/?page_id=386"},"modified":"2019-05-29T17:33:16","modified_gmt":"2019-05-29T17:33:16","slug":"lab-1","status":"publish","type":"page","link":"https:\/\/sites.rutgers.edu\/demetrios-lambropoulos\/program-methodology-i-lab-summer-2019\/lab-1\/","title":{"rendered":"Lab 1"},"content":{"rendered":"

Part 1 – Understand your compiler<\/h1>\n
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<\/h2>\n

1.1 – Compiling a program via Command Line<\/h2>\n
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We will primarily use the Linux terminal in examples. Any IDE may be used, but programs must be able to compile in the B-125 computer lab.<\/p>\n

Step 1: Open your Terminal<\/strong><\/p>\n

Step 2: Type “cd”<\/strong><\/p>\n

Step 3: Type “mkdir Lab1”<\/strong><\/p>\n

Step 4: Type “cd Lab1”<\/strong><\/p>\n

Step 5: Type “nano hello.cpp” and enter the following code<\/strong><\/p>\n

\n\n\n\n
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 1\r\n 2\r\n 3\r\n 4\r\n 5\r\n 6\r\n 7\r\n 8\r\n 9\r\n10\r\n11\r\n12<\/pre>\n<\/td>\n
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\/\/ This is a comment<\/span>\r\n\r\n#include <iostream><\/span>\r\n\r\nusing<\/span> namespace<\/span> std;\r\n\r\nint<\/span> main<\/span>()\r\n{\r\n     cout <<<\/span> \"Hello World\\n\"<\/span>; \r\n\r\n     return<\/span> 0<\/span>;\r\n}\r\n<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
 <\/p>\n
Step 6: Save the .cpp file by typing “Ctrl+O”, then [Enter] <\/strong><\/p>\n
Step 7: Exit nano by typing “Ctrl+X”<\/strong><\/p>\n
Step 8: Compile the C++ Program by typing “g++ -o hello hello.cpp” where hello is the executable or object file<\/strong><\/p>\n
Step 9: Run the executable by typing “.\/hello” in the terminal<\/strong><\/p>\n
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 <\/p>\n
 <\/p>\n
1.2 – Flags for command line<\/h2>\n
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Most common GCC and Clang compiler flags<\/p>\n
 <\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
std Flags<\/strong><\/td>\nSpecify the C++ version or ISO standard version.<\/td>\n<\/tr>\n
-std=c++11<\/td>\nSpecifies ISO C++11<\/td>\n<\/tr>\n
-std=c++14<\/td>\nSpecifies ISO C++14<\/td>\n<\/tr>\n
-std=c++1z<\/td>\n<\/td>\n<\/tr>\n
-std=c++20<\/td>\n<\/td>\n<\/tr>\n
-std=gnu++<\/td>\n<\/td>\n<\/tr>\n
Verbosity Flags<\/strong><\/td>\nW stands for warning<\/td>\n<\/tr>\n
-Wall<\/td>\nTurns on different compiler warning flags such as -Waddress, -Wcomment, -Wformat, -Wbool-compare, -Wuninitialized, -Wunknown-pragmas, -Wunused-value, …<\/td>\n<\/tr>\n
-Werror<\/td>\nTurns any warning into a compilation error<\/td>\n<\/tr>\n
-Wextra<\/td>\nEnables flags that are not enabled with -Wall<\/td>\n<\/tr>\n
-pendantic or -Wpendantic<\/td>\nIssue all warning required by ISO C and ISO C++ standard, it issues warning whenever there are compiler extensions non compliant to ISO C or C++ standard.<\/td>\n<\/tr>\n
-Wconversion<\/td>\n<\/td>\n<\/tr>\n
-Wcast-align<\/td>\n<\/td>\n<\/tr>\n
-Wunnused<\/td>\n<\/td>\n<\/tr>\n
-Wshadow<\/td>\n<\/td>\n<\/tr>\n
-Wold-style-cast<\/td>\n<\/td>\n<\/tr>\n
-Wpointer-arith
\n-Wcast-qual
\n-Wmissing-prototypes
\n-Wno-missing-braces<\/td>\n		<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
 <\/p>\n
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<\/h2>\n
1.3 – Writing your first Makefile<\/h2>\n
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In this section we are going to continue working with the hello.cpp file that was created in Section 1.1.<\/p>\n
Step 1: Type “nano Makefile” and type the contents from below.\u00a0<\/strong><\/p>\n
<\/p>\n
\n\n\n\n
\n
 1\r\n 2\r\n 3\r\n 4\r\n 5\r\n 6\r\n 7\r\n 8\r\n 9\r\n10\r\n11\r\n12\r\n13\r\n14<\/pre>\n<\/td>\n
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CC<\/span>=<\/span>g++\r\n\r\nCFLAGS<\/span>=<\/span>-g -Wall -Wpedantic -Werror\r\n\r\nall<\/span>:<\/span> main<\/span>\r\n\r\nhello.o<\/span>:<\/span> hello.cpp<\/span>\r\n        ${<\/span>CC<\/span>}<\/span> ${<\/span>CFLAGS<\/span>}<\/span> -c hello.cpp\r\n\r\nmain<\/span>:<\/span> hello.o<\/span>\r\n        ${<\/span>CC<\/span>}<\/span> ${<\/span>CFLAGS<\/span>}<\/span> -o main hello.o\r\n\r\nclean<\/span>:<\/span>\r\n        ${<\/span>RM<\/span>}<\/span> *.o main\r\n<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
 <\/p>\n
Step 2: Save the file and exit<\/strong><\/p>\n
 <\/p>\n
Sections Explained:<\/p>\n
Line 1: CC=g++<\/strong> – Specifies the compiler. gcc<\/strong> for C programs and g++<\/strong> for C++ programs<\/p>\n
Line 3: CFLAGS<\/strong> – Specifies the compiler flags to be applied when compiling the programs.<\/p>\n
The first flag that is used when compiling is the\u00a0-g<\/strong> flag which tells the compiler to add debugging information to the executable file. The\u00a0-Wall<\/strong> flag, as described above, turns on most of the warning flags for the compiler. The\u00a0-Wpedantic<\/strong> flag will issue warnings when there are noncompliant compiler extensions used. The\u00a0-Werror<\/strong> flag will turn any warning from the compiler into an error.<\/p>\n
Line 5: all: main<\/strong> – Specifies the targets to be made<\/p>\n
Line 7: hello.o: hello.cpp\u00a0<\/strong>– Creates the object file\u00a0hello.o<\/strong> from the source file\u00a0hello.cpp<\/strong><\/p>\n
Line 8<\/strong> uses the\u00a0CC<\/strong> and\u00a0CFLAGS<\/strong> variables that we defined earlier in the Makefile and invokes the compiler with the\u00a0-c<\/strong> flag<\/p>\n
Line 10: main: hello.o<\/strong> – Creates the executable file from the previously generated object file<\/p>\n
Line 11<\/strong> uses the\u00a0CC<\/strong> and\u00a0CFLAGS\u00a0<\/strong>variables that was defined earlier in the Makefile and links the generated object file to the executable\u00a0main<\/strong><\/p>\n
Line 13: clean:<\/strong> – Specifies what is executed when “make clean” is called<\/p>\n
Line 14:\u00a0<\/strong>Tells “make clean” to remove all object files (files ending in .o) and the target executable\u00a0main<\/strong><\/p>\n
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<\/h2>\n
1.4 – Compiling a program with a Makefile<\/h2>\n
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In order to compile with the Makefile that we just created type “make” into the terminal. When you examine your working directory you will notice two new files titled “hello.o” and “main”. “main” is an executable file that can be run by typing “.\/main” into the terminal.<\/p>\n
The “clean” section we defined in the Makefile can be used to clean our working directory from all files ending in “.o” and the file main. This can be utilized by typing “make clean” into the terminal.<\/p>\n
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<\/h1>\n
Part 2 – Writing Programs<\/h1>\n
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When writing the following programs you will want to take in user input as arguments to your program. This can be done by changing main()<\/strong> to main(int argc, char **argv)<\/strong>.\u00a0argc<\/strong> is an integer value representing the number of command line arguments the user enters, including the name of the program.\u00a0argv\u00a0<\/strong>stands for ARGument Vector and is an array of character pointers which contains all the command line arguments including the name of the program at argv[0]<\/strong>. An example of using both the\u00a0argc<\/strong> and\u00a0argv<\/strong> values can be seen as follows:
\n<\/p>\n
\n\n\n\n
\n
 1\r\n 2\r\n 3\r\n 4\r\n 5\r\n 6\r\n 7\r\n 8\r\n 9\r\n10\r\n11\r\n12\r\n13\r\n14<\/pre>\n<\/td>\n
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#include <iostream> <\/span>\r\nusing<\/span> namespace<\/span> std; \r\n  \r\nint<\/span> main<\/span>(int<\/span> argc, char<\/span>**<\/span> argv) \r\n{ \r\n    cout <<<\/span> \"You have entered \"<\/span> <<<\/span> argc <<<\/span> \" arguments:\"<\/span> <<<\/span> \"<\/span>\\n<\/span>\"<\/span>; \r\n  \r\n    for<\/span> (int<\/span> i =<\/span> 0<\/span>; i <<\/span> argc; ++<\/span>i) \r\n    {\r\n         cout <<<\/span> argv[i] <<<\/span> \"<\/span>\\n<\/span>\"<\/span>; \r\n    }\r\n\r\n    return<\/span> 0<\/span>; \r\n} \r\n<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
 <\/p>\n
Say we compiled the above program with the following command<\/p>\n
g++ -o main example.cpp<\/strong><\/p>\n
and then ran the executable as follows<\/p>\n
.\/main programming methodology is fun<\/strong><\/p>\n
you will achieve the following output.<\/p>\n
You have entered 5 arguments:
\n.\/main
\nprogramming
\nmethodology
\nis
\nfun<\/strong><\/p>\n
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<\/h2>\n
2.1 – Question 1<\/h2>\n
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Given a positive integer denoting n, do the following:<\/p>\n