jonatanP1993 lab1 submission

ANSWERS.md

@@ -19,128 +19,215 @@ Please use [markdown](https://help.github.com/articles/markdown-basics) formatin
 
 Make another directory inside the `unixstuff` directory called `backups`
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** *mkdir backups*
 
 ###Exercise 1b
 
 Use the commands `cd`, `ls` and `pwd` to explore the file system.
 
 (Remember, if you get lost, type `cd` by itself to return to your home-directory)
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** *cd = change directorie, ls = lists the content of current directorie, pwd = currentworking directorie.*
 
 ###Exercise 2a
 
 Create a backup of your `science.txt` file by copying it to a file called `science.bak`
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** *cp science.txt science.bak.*
 
 ###Exercise 2b
 
 Create a directory called `tempstuff` using `mkdir`, then remove it using the `rmdir` command.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** *mkdir tempstuff, rmdir tempstuff.*
 
 ###Exercise 3a
 
 Using the above method, create another file called `list2` containing the following fruit: orange, plum, mango, grapefruit. Read the contents of `list2`.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** *
+    cat > list2
+    orange
+    plum
+    mango
+    grapefruit
+    ^D
+
+    cat list2*
 
 ###Exercise 3b
 
 Using pipes, display all lines of `list1` and `list2` containing the letter 'p', and sort the result.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** *cat list1 list2 | grep p | sort*
 
 ###Exercise 5a
 
 Try changing access permissions on the file `science.txt` and on the directory `backups`.
 
 Use `ls -l` to check that the permissions have changed.
 
-**Answer:** *YOUR ANSWER HERE*
+**Answer:** *chmod -w sience.txt  remove write access. chmod +w science.txt. chmod -rw backups made OS write out a warning when deleted.*
 
 ##Shell questions
 
 1. What option with the command `rm` is required to remove a directory?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *-r*
 1. What is the command used to display the manual pages for any command?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *man*
 1. What command will show the first 5 lines of an input file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *head -n 5*
 1. What command can be used to rename a file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *mv*
 1. What option can we given to `ls` to show the hidden files?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *-a*
 1. What will the command `cat -n file` do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *it numbers each line the file*
 1. What will the command `echo -n hello` do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *does not print the newline character.*
 1. What command will display s list of the users who currently logged in in the system?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *who*
 1. How do you change password on your account?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *passwd*
 1. How can you list a file in reverse order?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *tail*
 1. What does the `less` command do?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *dispay one page at a time*
 1. With `less` how do you navigate?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *spacebar, pageUp, pageDown and q*
 1. What command will display the running processes of the current user?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *top -u*
 1. What command can be used to find the process(es) consuming the most CPU?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *top*
 
 ##vi questions
 1. How do we save a file in `vi` and continue working?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *:w*
 1. What command/key is used to start entering text?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *i*
 1. What are the different modes the editor can be in?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *command mode or insert mode*
 1. What command can be used to place the cursor at the beginning of line 4?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *:4*
 1. What will `dd` command do (in command-mode)?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *delete current line*
 1. How do you undo the most recent changes?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *u*
 1. How do you move back one word?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *b*
 
 ##The C Language and Make tool Questions
 
 1. How do you use `gcc` to only produce the `.o` file?  What is the difference between generating only the `.o` file, and building the `hello` executable done in the previous compilation above?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *gcc-c hello.c -o hello.o, can be used to share with other, and then linked together to make an executable.*
 1. Give the command for compiling with `debug` enabled instead of normal compilation for the two examples shown in Listing 2 and Listing 3. Explain how to turn debugging on/off for the two cases.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** * gcc -DDEBUG hello.c -o hello*
 1. Give a brief pros and cons discussion for the two methods to add debug code shown in Listing 2 and Listing 3.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *Listing 2 is clearly better than Listing 3. Listing 2 will have its filesize reduced if not in debugmode. While Listing 3 has the same size no matter what mode it is compiled in.*
 1. Provide the command for generating the *map* file. Which of the `gcc` tools is responsible for producing a *map* file?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *gcc -o hello -Wl,-Map=hello.map hello.c, Linker is responsible for producing the map file.*
 1. What is the content of each of the sections in a *map* file. Explain briefly.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *It shows where the different data types are stored in memory.*
 1. Rewrite `hello.c` to produce entries in the *map* file for `.data`, `.bss`, and `.rodata`. Hint: This can be done by adding one variable for each type to the file.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *added: int i; int debug = 1; static int a = 1;*
 1. Add the following function to `hello.c`: `double multiply(double x1, double x2)`, which returns `x1*x2`. Use `gcc` to generate an assembly code listing for the program, and examine the assembly code. What assembly instructions are used to do this? Repeat this task, but now replace `double` with `float`. Explain!
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *double -> mulsd, float -> mulss, no idea why, I guess the ALU in the processor has different tools for different datatypes.*
 1. How does `make` know if a file must be recompiled?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *it checks the datestamp on the files to see if any of the precompiled files have been changed since last compilation.*
 1. Provide a `make` command to use a file named `mymakefile` instead of the default `makefile`.
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *make -f mymakefile*
 1. How do you implement an *include guard*, and why is it needed?
-  - **Answer:** *YOUR ANSWER HERE*
+  - **Answer:** *you can do a #ifndef #endif check in the preprocessor area to skip code if there are more than one #include, include guards are needed to not violate 'one definition rule'.*
 
 ##Library Task
 
 Insert your code between the brackets `{}`:
 
     void main( int argc, char *argv[] )
-	{
+    {
+    	int tableSize;
+    double min = 0.0;
+    double max = 100.0;
+
+    if(atoi(argv[1])){
+    	tableSize = atoi(argv[1]);
+    }else{
+    	printf("You need to specify table size!");
+    }
+
+    double table[tableSize];
+    if(argc >= 3 ){
+    	min = atof(argv[2]);
+    }else {
+    	min = 0.0;
+    }
+    if(argc  >= 4){
+    	max = atof(argv[3]);
+    }else{
+    	max = 100.0;
+    }
+
+    srand(time(NULL));
+    int i;
+
+    for(i = 0; i < tableSize; i++){
+    	table[i] = randDouble(min,max);
+    }
+    printf("Here is our array :\n");
+    for(i=0; i < tableSize; i++){
+    	printf("%.2f, ", table[i]);
+
+    }
+
+    printf("and the sum: \n %.2f,\n ",tab_sort_sum(table, tableSize));
+
+
+    }
+
+
+
     }
 
-	double tab_sort_sum( double *tab, int tab_size )
-	{
-	}
+    double tab_sort_sum( double *tab, int tab_size )
+    {
+    	double table[tab_size];
+    double sum;
+    int i;
+
+
+    for(i= 0; i < tab_size; i++){
+    	table[i] = tab[i];
+    }
+
+
+
+    for(i=0; i < tab_size -1; ++i){
+    	int j;
+    	double temp;
+    	int  min = i;
+    	for(j= i+1; j < tab_size; ++j){
+    		if(table[j] < table[min]) min = j;
+    			}
+    			temp = table[i];
+    			table[i] = table[min];
+			table[min] = temp;
+    	}
+
+
+
+
+
+    printf("\nThe sorted list\n");	
+    for(i = 0; i < tab_size; i++){
+    	printf(" %.2f ", table[i]);
+    }
+    printf("\n");
+    for(i = 0; i < tab_size; i++){
+    	sum += table[i];
+
+    }
+    return sum;
+    }
+