Systems Programming (XMUT)
Exercise 3: Linked Lists, File I/O and More

days Due 1 December 7 pm

To Submit:

  • activity1.c
  • activity2.c
  • activity3.c

ALERT! Do not rename these files.

Objective

This exercise aims to write and debug programs using linked lists, file stream input/output, and command-line arguments.

Activity 1: Linked List [30 Marks]

Copy and paste the following C program to your favourite text editor (You can extract a copy of this file from Zip Files): 

#include <stdio.h>

// (1) Complete linked list node declaration below.
//     Do not change the name of the structure.
struct node {

};

int main(void)
{
   struct node *head = NULL; // head points to the head of list
   struct node *tmp;
   
   // This for-loop will build a list
   for(int i = 0; i < 10; i++) {
      // (2) Use malloc() or calloc() to allocate memory for one node
      //     and let tmp point the the allocated memory.

      // (3) Assign 100*(i+1) to data and let next point to NULL.   
   
      // (4) Append tmp to the list pointed by head
   }
   
   struct node *rover = head;
   while(rover) {
      printf("%d ", rover->data);
      rover = rover->next;
   }
   printf("\n");
   
   return 0;
}

Save the file as activity1.c. Study the source file and do the following within the file:

  • Define a structure named node to represent a singly linked list node. The structure should have two parameters
    • data: an integer
    • next: pointer to next node in the list
  • Use either malloc() or calloc() to allocate memory for one node and let tmp point the the allocated memory.
  • Assign 100*(i+1) to the data member of the node and let the next member point to NULL.
  • Append the newly created node pointed by tmp to the list pointed by head. (Append means insert after the current last element in the list.)

Your program should not output anything aside from the output generated by printf() in lines 26 and 29.

right Compile and run the program. If you are happy with the program, submit it to the Assessment System for marking.

Activity 2: Text File Processing 2 [30 Marks]

In this activity, you will perform simple text file processing using file stream I/O. Suppose you are given a text file named raw.txt, which contains 2 decimal numbers per line: 

12 134
100 94
23 324
10 45

Copy and paste the following C program. to your favourite text editor (You can extract a copy of this file from Zip Files): 

#include <stdio.h>

int main(void)
{
    int a, b;
    FILE *in; // use for handling input file
    FILE *out; // use for handling output file

    // Open raw.txt for reading
       
    // Open processed.txt for writing
    
    // Go thru raw.txt file and generate processed.txt file accordingly
    
    return 0;
}

Save the file as activity2.c. Use activity2.c as a starting point to write a program that will add the numbers in every line of raw.txt and output the numbers together with the sum to a file named processed.txt. The contents of processed.txt should look like this: 

12 134 146
100 94 194
23 324 347
10 45 55

right You can use the file raw.txt included in Zip Files to test your code. If you are happy with the program, submit it to the Assessment System for marking.

Hint: If you are using fscanf() to scan the contents of the file, you may want to pay close attention to its return value.

Activity 3: Command-Line Arguments [40 Marks]

In this activity, you will write a C program that accepts an arbitrary number of command-line arguments. The program should treat every command-line argument (excluding the program name itself) as an integer. The program should add all the integers and print the sum to the display. For instance, suppose you compile the program into an executable file named activity3, then if the program is executed as 

./activity3 1 2 3 4 5 6

the output should be 
21

If the program is executed as 

./activity3

the output should be 

0

right Save the program as activity3.c. To have an easier time with the auto-marking script, make sure that the output only consists of the sum followed by a newline character.

If you are happy with the program, submit it to the Assessment System for marking.

Hint: You may use sscanf() to convert a string to an integer.

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