1 C/C++ UM/MCSR Last modified: September 3, 2008

2 Outline Surfing websitewww.mcsr.olemiss.edu Logging into the system via ssh Brief History of C/C++ languages Basic Structure and Syntax of C/C++ Programs A quick glance on PICO editor A detailed look on compilers and compiling commands How to run a compiled file Application of C/C++ Compiling

3 Logging into the system using ssh Logging into the system from Windows: –Start the secure shell client: Start->Programs->SSH Secure Shell->Secure Shell Client –Connect to willow: From the secure shell window, click Quick Connect. Then, from the Connect to Remote Host pop-up window, enter: Hostname: HostName User Name: UserName Click Connect. Logging into the system from Unix: –Start the Terminal: Finder  Utilities  Terminal –Type the following command: ssh Enter your password If you are a windows user and you want to download ssh: Go to MCSR Web at and click on the Software Tab, followed by the Secure Shell link. If you are a Unix, Linux, or MAC user, ssh will come with the operating system

4 A Brief History of C language In the early 1970s, Dennis Ritchie of Bell Laboratories was engaged in a project to develop new operating system. C programming language was then developed. In the early 1980's, also at Bell Laboratories, another C++ language was created. This new language was developed by Bjarne Stroustrup and was called C++ which was designed with OOP (Object Oriented Programming) features added to C without significantly changing the C component.

5 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230

6 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 Comments are set between /* and */

7 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 The C pre-processor replaces this directive with the contents of the stdio.h header file from the standard C library.

8 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 Every C program must have one main function.

9 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 Each variable must be explicitly defined as a specific type.

10 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 The stdio library defines the printf() function for creating output.

11 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 The stdio library defines the printf() function for creating output. \n is the newline character

12 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 The stdio library defines the scanf() function for capturing input.

13 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 %d tells scanf() to interpret the input as a decimal value

14 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 The = operator is used for assignment. The * operator is used for multiplication.

15 A Simple C Program /* Take a number multiply it by 10 and display it */ #include main() { int number, result; printf("Type in a number \n"); scanf("%d", &number); result = number *10; printf("The number multiplied by 10 equals %d\n", result); } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 %d tells printf() to treat the value of the result variable as a decimal nbr.

16 Simple C++ Program /* Take a number multiply it by 10 and display it */ #include int main() { int number, result; std::cout<<"Type in a number “<< std::endl; std::cin>>number; result = number *10; std::cout<<"The number multiplied by 10 equals “<<result; } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 C++ pre-processor directives include different versions of the standard library packages.

17 Simple C++ Program /* Take a number multiply it by 10 and display it */ #include int main() { int number, result; std::cout <<"Type in a number “<< std::endl; std::cin >>number; result = number *10; std::cout<<"The number multiplied by 10 equals “<<result; } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 std is an object which you can send messages to—messages such as: cout, cin, & endl.

18 Simple C++ Program /* Take a number multiply it by 10 and display it */ #include using namespace std; int main() { int number, result; cout <<"Type in a number “ << endl; cin>>number; result = number *10; cout<<"The number multiplied by 10 equals “ <<result; } Sample Program Output Type in a number 23 The number multiplied by 10 equals 230 You can use an object’s namespace, to keep from having to specify the name of the object each time you send it a message.

19 The PICO Editor General Command –Write editor contents to a file[Ctrl] o –Save the file and exit pico[Ctrl] x –Spell Check[Ctrl] t –Justify the text[Ctrl] j Moving around in your file –Move one character to the right[Ctrl] f or right arrow key –Move one character to the left[Ctrl] b or left arrow key –Move up one line[Ctrl] p or up arrow key –Move down one line[Ctrl] n or down arrow key

20 C/C++ source files suffixes.cpp,.cc,.c suffixes are used for C++ programs that are to be preprocessed, compiled and assembled.c for C programs that are to be processed, compiled and assembled.h or preprocessor (header) files

21 How to run compiled files The compiling commands create an executable file known as a.out unless specified otherwise. To execute your program, type./a.out and press Enter.

22 Compilation Details object.h object.cpp main.cpp object.s main.s object.o main.o Output Source codeAssemblyMachine Code

23 A detailed look into Compilers and Compiling commands C/C++ Compilers at UM/MCSR: –Intel C++ Compiler on redwood –MIPS C, MIPSpro C, and MIPSpro C++ version 7.4 compilers on Origin 2800 sweetgum –Portland Group, GNU, and MPICH Compilers on Beowulf Cluster mimosa –GNU C Compiler and SUN STUDIO 8 C/C++ Compilers on willow

24 Loading the appropriate Intel Compiler Module Several versions/builds of Intel compilers are available on redwood. To compile, you must first pick which compiler version module you want to load, then load it. Before you can use the module command, you must source the correct setup file for your shell. –. /usr/share/modules/init/sh (if using ssh) (There should be a space between. and /opt) Then you use the module command: –module list (to see if any other versions of compiler modules are loaded) –module purge (to unload any other versions of compiler modules) –module list (to verify that other versions were successfully unloaded) –module avail (to see what versions of compiler modules are available to load) For example, to load the latest 10.1 version of the C Compilers: –module load c101 –module list These are the names of the modules and the compiler versions they correspond to: –intel-compilers for c 7.1 –intel-compilers for c 8.0 –intel-compilers for c 8.0 –intel-compilers for c 9.0 –intel-compilers for c 9.1 –intel-compilers.cc for c 10.1

25 Intel C++ Compiler on redwood Intel C/C++ Compilers(7.1, 8.0, 9.0, 9.1 & 10.0) –Before using the C/C++ Compiler on redwood, you must first load the appropriate Intel compiler module. –Then, to compile: icc example.c if using the 8.0 or later compiler ecc example.c if using the 7.1 compiler. With Intel compilers, the invocation syntax is the same regardless of whether your source file is C or C++.

26 Exercise 1: Intel Compiler on Redwood 1.If you have an account on redwood, login to it. 2.Copy the two example source files from /usr/local/examples/c to your working directory: A.cd 1 (if using a common class account, cd to your numbered subdirectory) B.cp /usr/local/examples/c/hello.c./hello.c C.cp /usr/local/examples/c/addtwo.cpp./addtwo.cpp 3.Source the appropriate modules environment script for your shell: C.. /usr/share/modules/init/bash 4.Use “module avail” to see which modules are available 5.Load one of the 10.X modules A.module load c101 B.module list 6.Compile/execute the hello.c and addtwo.cpp A.icc hello.c B../a.out C.icc addtwo.cpp D../a.out 7.Clear all loaded modules A.module list B.module clear C.module list

27 Sweetgum and Mimosa Sweetgum: MIPSPro 7.4 Compilers, version 7.4 –To compile with cc/CC on sweetgum, enter: CC example.c –To find out more about compilers, enter: man cc OR man CC Mimosa: PGI CDK 7.2 Compilers –To compile with the C/C++ compilers, enter: /usr/local/apps/pgi-7.2/linux86/7.2/bin/pgCC example.c

28 GNU C Compiler and SUN STUDIO 8 C/C++ Compilers on willow gcc file1.c command is used to compile and link a C program on willow g++ file1.c command is used to compile and link a C++ program on willow

29 Willow & Common Compiler Flags Sun Studio C/C++ Compilers, Version 5.5: –To compile with C/C++, enter: cc example.c (C) CC example.c (C++) –Compilers located in /ptmp/studio8/SUNWspro/bin GNU C/C++ Compilers, Version – To compile with C/C++, enter: gcc example.c (C) g++ example.c (C++) –Compilers located in /usr/local/bin Use which to see which compiler version is being found. –which cc –which CC If there are no compilation errors this creates an executable file called a.out. To execute the C/C++ program, enter:./a.out.

30 Exercise 2: Compile C/C++ on willow 1.Log in to willow using the account: student 2.Change to your numbered working directory: –cd 1 3.Compile/execute hello.c using GNU C compiler –gcc hello.c –./a.out 4.Compile/execute simpleB.cpp using Sun’s C++ –CC simpleB.cpp –./a.out 5.Try to compile hello.c using Sun’s C compiler –cc hello.c

31 Example C/C++ Flags cc -c Compile or assemble the source files, but do not link. -S Stop after the stage of compilation proper -E Stop after the preprocessing stage -o newFilename Name executable something besides a.out -V Show the compiler version (SUN) -vShow the compiler version (GNU)

32 Exercise 3: Compiler Options 1.Compile/execute hello.c using GNU C compiler, and name the executable file helloc.exe –gcc hello.c –o helloc.exe –./helloc.exe 2.Determine what version of the GNU compilers are installed –gcc -v –g++ -v 3.Determine version of installed Sun’s compiler –CC –V –/ptmp/studio8/SUNWspro/bin/cc -V

33 Frequently Asked ?’s on C/C++ Willow 1.How can I compile one or more C/C++ source files into object files without yet linking into an executable program? 2.How can I ensure the compiler will find a C/C++ header file referenced by my program? 3.How can I ensure the compiler will find a pre- compiled module referenced by my program but residing in a system- or user-defined archive library? 4.How can I add my own module to a library archive for others on the system to re-use? Answers here (or in Advanced C/C++ Compiling Unix Camp)