A project for C/C++, Data Structures, and System Programming by Karl Krauss for fall 2011.

Approximately 1 hour

The purpose of this project was modify a program allowing for input from a file and sorting to monitor.

• file i/o

• Pointers
• Sorts
• file i/o

• command line arg
• i/o redirection
• file io
• directories
• file attributes
• processes
• timer
• threads

This is the code:

/*  This is the latered version allowing for the input to come from a file and the output to be stdout
  * EoCEsrc.c - sample code for use with EoCE
  *
  * To compile: gcc -o eoceprog EoCEsrc.c -lpthread
  * To execute: ./eoceprog 55 44 33 22 11 12 23 34 45 5 1 3 4 2
  *
  */
 #include<stdio.h>
 #include<stdlib.h>
 #include<pthread.h>
 #include<unistd.h>
 
 struct localinfo {
     unsigned char value;
 };
 
 FILE *fPtr;
 
 int main(/*int argc, char **argv*/) // since the input is coming from a file there is no need for argc or argv
 {
     void *process(void *);
     unsigned char x; // simply changed this to an x(personal preference) and this will be used several times later on
     struct localinfo local;
	 unsigned char valueCount =1; // since there is no argc I need a place to store how MANY values are in the file to be sorted
								// we are assuming at least one value in the file
 
 
     /*if (argc < 2)  No longer needed since no argc
     {
         printf("Please provide a list of positive unique whole numbers,\n");
         printf("between 1 and 255\n");
        exit(1);
     }
 
     if (argc > 255)
     {
         printf("Please provide less than 256 arguments,\n");
         printf("between 1 and 255\n");
         exit(1);
     }  no longer needed since no argc */  
 
     fPtr = fopen("valuefile", "r"); // changed to r since we are reading
     if(fPtr == NULL)
     {
         printf("Error opening file\n");
         exit(1);
     }
     char c;  // we are going to assume that values are seperated by a space not a newline and the following loop will count how many values we have
	 while ((feof(fPtr)) == 0)// this checks if it is end of file if it is not then we want to try and count
	 {
			if ((c = fgetc(fPtr)) == ' ') // this checks for spaces as each space would indicate a new value
			{
				valueCount++; // if the char grabbed by fgetc DOES equal ' '(a space) then we want to incriment the valueCount
			}
 
	}
	unsigned char value[valueCount]; // I am crating an array of the size value count to store all of the values from the file
	pthread_t threads[valueCount];
 
	fclose(fPtr);
	fPtr = fopen("valuefile", "r");  // this is resetting the file descriptor to the beginning of the file. (many ways to do this) 
 
	 if(fPtr == NULL)
     {
         printf("Error opening file\n");
         exit(1);
     }
 
 
	for(x=1; x<=valueCount; x++)
	{
		fscanf(fPtr, "%hhu", &value[x]);  // this loop is how I copy each numeric value seperated by a space into my value array
	}
 
    fclose(fPtr);  // the file is no longer needed, have stored how many values there are, and each value into an array.  
 
	for(x=1; x<=valueCount; x++) // now we are getting back into the original code(minor changes) 
    {
       local.value = /*(unsigned char)atoi*/(value[x]); // do to the fact I created the value array AS unsigned char I do not need to cast
       pthread_create(&threads[x], NULL, (void *) process, (void *) &local); 
       usleep(32);
    }
 
    for(x=1; x<=valueCount; x++)
    {
		pthread_join(threads[x], NULL);
	}
 
     return(0);
 }
 
 void *process(void *foreign)
 {
     struct localinfo *thing = foreign;
     unsigned char data = thing -> value;
     sleep((int)(data & 0xFF));
     printf("%hhu ", data);
     fflush(stdout);
 }