COMPSCI 210 Semester 1 - 2014

1. COMPSCI 210Semester 1 - 2014 Tutorial 7 – C Exercises

2. Downloading and unpacking examples.tar.gz from Cecil • Download examples.tar.gz from Cecil into your hard drive • Go to: http://afsweb.ec.auckland.ac.nz/

3. Downloading and unpacking examples.tar.gz from Cecil cont. • You will be directed to • Select unixhome • You will be directed to • Select Upload File(s) • Navigate to where you downloaded examples.tar.gz and upload it

4. Using University UNIX Account • Connect from MS Windows using Putty • All programs -> Putty • Under-grad server is login.cs.auckland.ac.nz • Login using your UPI and password • You can access the machine from home if you have Putty installed on your home machine From: S1-Basic C programming lecture’s slides

5. Login using your UPI and password

6. Login using your UPI and password cont.

7. Unpacking examples.tar.gz • tar xvfexamples.tar.gz

8. Compile and Run the countdown Program name of executatble • Compile • gcc -o countdowncountdown.c • Run name of source code $ ./countdown Enter a positive number: 6 6 5 4 3 2 1 0 From: S1-Basic C programming lecture’s slides

9. Compile and Run the countdown Program

10. Basic Linux Commands • Creating a directory … mkdirdirname • Example: mkdir Assignment3 • Changing a directory … cd dirname • Example: cd Assignment3 • Going back to the home directory: cd • Listing the content of a directory… ls • Deleting a directory… rm -rfdirname • Example: rm-rfAssignment3 … it deletes the folder and its contents

11. Exercise I Write a C code to breakdown www.auckland.ac.nz web address into: www auckland ac nz

12. #include <string.h>Strtok() char * strtok (char *restrict newstring, const char *restrict delimiters) • A string can be split into tokens by making a series of calls to the function strtok • The string to be split up is passed as the newstring argument on the first call only • Subsequent calls to get additional tokens from the same string are indicated by passing a null pointer as the newstringargument • The delimiters argument is a string that specifies a set of delimiters that may surround the token being extracted • On the next call to strtok, the searching begins at the next character beyond the one that marked the end of the previous token • Note that the set of delimiters delimiters do not have to be the same on every call in a series of calls to strtok • If the end of the string newstring is reached, or if the remainder of string consists only of delimiter characters, strtok returns a null pointer. Retrieved from: http://www.gnu.org/software/libc/manual/html_node/Finding-Tokens-in-a-String.html

13. Solution #include <string.h> #include <stdio.h> int main() { char address[40] = "www.auckland.ac.nz"; char delimiter[2] = "."; char *token; /* get the first part */ token = strtok(address, delimiter); /* get the rest */ while( token != NULL ) { printf( " %s\n", token ); token = strtok(NULL, delimiter); } return(0); }