In this introduction to UNIX, only the dumb terminal (also known as the command line ) interface is discussed.

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1 COE808 Lab1: C programming lab Prelab preparation Before coming to the lab you should: 1. Read the lab. The most recent version can be found at the URL: 2. Try to prepare any questions you may have about the lab. UNIX quickstart Basic UNIX usage Although the UNIX operating system can present a graphical user-friendly interface, it also excels at provding a purely text-based dumb terminal interface where you enter commands and get the results. In this introduction to UNIX, only the dumb terminal (also known as the command line ) interface is discussed. We now examine an extremely tiny subset of these commands. The directory contents ls command This command lists (ls is short for list ) the contents of the current directory. If invoked with the options -l, a long listing is produced providing more detail about each item in directory such as its owner, size, and modification date. The make directory mkdir command The mkdir directory command creates a new directory. (Note: the words directory and folder are synonyms.) The change directory cd command The cd directory command changes the current directory to the named directory. The directory named.. (i.e. dot dot) refers to the parent of the current directory. For example: mkdir mydirectory Creates a new folder called "mydirectory" cd mydirectory Makes the newly created folder the current one ls List the contents of "mydirectory" cd.. Goes back to the original directory ls List the contents of the original directory 1

2 The copy cp command The cp sourcefile copiedfile copies the first file to the second. For example: cp foo.c foo.cbakup Makes a bakup copy of foo.c mkdir BAK cp foo.c BAK/foo.c Makes a backup in another directory The unzip command The unzip zipfile unzips the named file. The remove(delete) rm command The rm file(s) deletes (permanantly) the named files. They cannot be recovered! REQUIRED EXERCISE To get started you must perform the following operations. Create your course directory with the command: mkdir coe Change to your course directory with the command: cd coe Create your lab1 sub-directory with the command: mkdir lab1 3. Change to your lab1 directory with the command: cd lab1 2

3 C Review/Tutorial (copying input to output) The mycopy.c program The C program shown below illustrates the basic copy filter application. Read the annotated source code and ensure that you understand each line. 1 /* Copy stdin to stdout */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * argv[]) 5 { int ch; while((ch = getchar())!= EOF) { putchar(ch); 10 exit(0) Type in the mycopy.c source code Type in the program as shown. Use any editor you want, but it is recommended that you use jedit or emacs. The name of the source code file you create must be mycopy.c. Compile the mycopy.c source code The file mycopy.c is converted to object code with the command: gcc -c mycopy.c Link and run the mycopy command Create the executable by linking the object code with the libraries using the command: gcc -o mycopy mycopy.o You should now be able to run your program by typing in the command: mycopy 3

4 Exercise 1 In this C exercise, you are going to parse the following program sample.txt into tokens, The name of the source code file you create must be scan.c. for(int i=0; i<5; i++) { // Print a quote mark (") emit("\""); // Print some stars and slashes (/* */) emit("/* */"); We can classify tokens as being either: ID: Identifiers KEY: Keywords OP: Operators PUNC: Punctuations LIT: Literals Please be noted that white space and comments should be ignored. Print out the following statistics: 1) The count of total tokens. 2) The count of how many times each token appears in the program Exercise 2 Write the program expr.c, which evaluates a reverse Polish expression from the command line, where each operator or operand is a separate argument. For example, * evaluates 2 * (3 + 4). Exercise 3 The name of the source code file you create must be table.c. Remember multiplication tables from elementary school? Well, today you will be printing out addition tables. An addition table is simply a table where the value of an entry is its row location plus its column location. See below for a more detailed specification. There are 4 functions you must implement to achieve your assignment. These are getint, printtable, printsrtable and of course main. They are described as follows: int getint(void) Gets a positive integer from the user and returns it. In the event of an error, return -1. 4

5 Integers on the input may be followed by either '\n' or EOF. void printtable(int rows,int cols) Prints out an addition table with the specified number of rows and columns. The table should have a border. Here is a sample output for 5 rows and 6 columns: The integers in your table should be spaced and lined up correctly for integers up to 3 digits in length. void printsrtable(int rows, int cols, int search, int replace) The function is very similar to printtable, except that the table printed out should have all instances of the number search replaced with the number replace. int main(int argc, char **argv) Your program will make use of command line arguments for some of its input. For this program, the first argument will be the number of rows and the second argument will be the number of columns. (ie, addtab 5 6 would produce a table with 5 rows and 6 columns.) Here is the order your program should run in: Read in the number of rows and columns from the command line arguments Print out the table Ask the user for the number to search for and the number to replace Print out the new table with the numbers replaced Exit, giving a friendly exit message If there are any errors encountered (bad user input, not enough command line arguments, etc) print out an appropriate error message and exit. Submitting your lab (1) Zip your lab1 assignment within your coe808 directory zip r lab1 lab1 (2) Attach your lab1.zip file and send to GA, Mr. Naimul Mefraz Khan, subject of your must be lab1 followed by your name and student id. n77khan@ryerson.ca 5