CSCI 101: Fundamentals of Computer Programming
Lab 11: Strings & Sorts
Fall 2005
Project #1
You are going to try running the proj1Solution file from the website during the lab to
ensure that you are able to do so. To execute the file, do the following:
a) Download the proj1Solution file from the website
a. Right click on the proj1Solution link and select Save Target As
b. Change the Save as Type to All Files
c. Make sure the filename is selected as proj1Solution
d. Save the file to your desktop
b) In your LabLaunch, run CoreFTP.
a. Connect to your aludra account by typing in your username and
password
b. A window will then pop up asking if you would like to save the key. Click
Yes.
c) Transfer the proj1Solution to your account
a. Go to your desktop on the left panel of the CoreFTP program
b. Go to the directory on the right panel where you wish to store the
proj1Solution file.
c. Drag the file from the left panel to the right. This will initiate the transfer.
d) Running the sample solution
a. Once you are done transferring, go to the directory where you store the file
in your aludra account.
b. Type in chmod 700 proj1Solution to change the permissions on the
file
c. Type in proj1Solution to run the program
Your TA/LA will then demonstrate to you how the program should work.
Strings
There are no string datatypes defined in C, and thus it is simulated using character arrays.
However, traditional operators such as the assignment operator “=”, addition operator
“+”, comparisons “>, <, >=” and so will not work on arrays. This is inconvenient as we
often come across situations when we would like to perform those operations.
The string.h header file provides an array of predefined functions that simulates such
operations on strings. The table below describes the more frequently used functions.
More information can be found at: http://www.cplusplus.com/ref/cstring/
char s1[10] = “string 1”;
char s2[10] = “string 2”;
char s3[10];
Assignment strcpy(s3,“string 3”); S3 = “string 3”
Concatenation strcat(s3,“concatenated”); S3 = “string 3 concatenated”
Comparison strcmp(s1, s2);
<0 if s1 < s2,
0 if s1 = s2,
>0 if s1 > s2
Table of functions in string.h
The sample program below should clearly illustrate the use of these three functions. Note
that you would need to include the string.h header file at the top of your program. You
may download this program at http://scf.usc.edu/~csci101/labs/lab11string.c
#include
#include
int main(){
char name1[20];
char name2[20];
int val;
printf("\nNames after initialization: \n");
printf("name 1 : %s\n", name1);
printf("name 2 : %s\n", name2);
strcpy(name1, "Mary");
strcpy(name2, "Arthur");
printf("\nNames after assignment: \n");
printf("name 1 : %s\n", name1);
printf("name 2 : %s\n", name2);
strcat(name1, " Jane");
strcat(name2, " Doyle");
printf("\nNames after concatenation: \n");
printf("name 1 : %s\n", name1);
printf("name 2 : %s\n", name2);
val = strcmp(name1, name2);
printf("\nComparison between name1 & name2: \n");
printf("val = %d\n", val);
return 0;
}
Sorting techniques
After the introduction of arrays, large amounts of data can now be stored and accessed
conveniently. However, as the amount of data increases, so does the complexity in
managing them. To ease this process, sorting techniques need to be introduced. You have
learnt three types sorting techniques introduced by Professor Ghyam during lecture:
bubble sort, insertion sort and selection sort. These three sorting techniques are generally
rather intuitive and easy to implement. However, the efficiency is compromised as they
are slower than other sorting techniques that are marginally harder and less intuitive.
Due to time constraints, we will only familiarize ourselves with the bubble sort. Like its
name sake, bubble sort is a sorting technique that “bubbles” up the smallest number in an
array. It compares two adjacent elements, and swaps them if it is in the wrong order. The
java applet at http://www.cs.hope.edu/~alganim/animator/Animator.html should clearly
illustrate this. Feel free to try out the other sorting algorithms (especially insertion and
selection sort).
The program below is an example of how bubble sort is implemented. You may
download it at http://scf.usc.edu/~csci101/lab11sort.c. Make sure you understand and
able to visualize how the sorting technique works.
#include
int main(){
const int size = 10;
int array[size];
int i, j, temp;
// Initializing and printing out an unsorted array
printf("\nUnsorted array: ");
for (i=0; i array[j]){
temp = array[j];
array[j] = array[j-1];
array[j-1] = temp;
}
}
// Printing out the array after every run of the sort
printf("\nRun %2d : ", i + 1);
for (j=0; j
