How to access UTA computer resources

If you are on campus, you can enter the following commands. If you are off campus, you must use Pulse Secure VPN first.


• Windows users:
  • Enter ssh abc1234@omega.uta.edu in the search box where abc1234 is to be replaced by your NetID.
    
    
    
    or
  • putty (small remote access client)
    
    
• Mac users: Terminal app -> omega.uta.edu

How to run a C program ?

1. Login to omega.uta.edu via DOS or putty.
   
2. $ nano -z myprogram.c
   "$" is the system prompt so do not type it. The "-z" is to enable control-z (temporarily exiting from nano - optional).
3. Save the file (Control-O) and Control-Z to temporarily exit from nano.
4. $ gcc myprogram.c
5. $ a.out
6. If there is a syntax error, go back to item 2 by issuing fg and re-edit the file.
   $ fg
7. If there is no syntax error, run the executable file.
   $ a.out
8. To quit from omega.uta.edu, enter exit, logoff or hit control-D.

Editors

• nano
• emacs
• vi

• nano command list

Characteristics of the C programming language

1. Structured programming
2. High portability
3. Precise manipulation of hardware
4. Free format
5. Collection of functions
6. Flexible data structures

Some peculiarities about the C programming language

1. A statement must end with ";" (semicolon).
2. A program is a set of functions each of which returns a value.
3. A function must have an argument even though it's empty (void).
4. A comment must start with /* and end with */.
5. All the variables must be declared first.
6. The function, main(), is the first program to be executed.
7. A statement "#include < stdio.h > " must be placed before the main function.
8. etc...

Comparison between C and FORTRAN

Unix command primer

1. ∧f (forward) ∧b (backward) ∧d (delete) ∧k (kill) ∧p (previous) ∧n (next) ∧a (top of line) ∧e (end of line)
2. ∧z (exit to command line temporarily)
   $ fg (to back to nano (or emacs))
3. $ gcc program.c ; a.out
4. $ rm myfile.c
   (delete file)
   
   Once deleted, the file cannot be restored. You can delete multiple files using a wild card (*) as
   $ rm myfile.*
   
   If you want to delete all the files in your directory (but you know the consequences), issue
   $ rm *.*
5. $ ls
   
   You can add an option to control the output. For example, to get more information for individual files, issue
   $ ls -lg
6. $ mv oldname.c newname.c
7. $ cp original.c new.c
8. $ cat program.c (content)
   
   $ more program.c
9. $ exit
   $ logout
   $ ∧d
10. To copy your C program to a PC application: Highlight the range and right click the toolbar, Edit, Copy, then control-V (paste).

Command line editor and nano (or emacs)

C syntax

• A C program is a set of functions.
• A function is a code to return a value upon exit where the returned value must be one of the int (integer), float (floating, real numbers), double (double precision real numbers) or char (a character, a special case of integer) types.
• The syntax of a function is

  type name(type argument) { statement1; statement2; .........; .........; /* comment1 comment2 */ some_function(some_argument); return value; }

  Example:

  int main() { float a; if (a>0) printf("Hello\n"); return 0; }
• A special function main is the one to be executed first. ANSI recommends that the main function is of integer type and returns 0 value upon exit.
• If a function is called (used) within another function, that called function must be defined elsewhere.

Skeleton C programs

int main()
{
return 0;
}

#include <stdio.h>
int main()
{
printf("Hello world\n");
return 0;
}

• The program above prints a string "Hello world" followed by a new line (\n).
• Since it uses a function, printf, that function must be defined somewhere. The first line calls a file, stdio.h, which is stored in the system file area. Most of the basic I/O functions are located in stdio.h.
• Here is a link to the list of functions defined in the ANSI standard C library.
• The first line #include is called a preprocessor directive, not part of the C program.
• \n is a special character that represents the next line.
• A function must have a type of the value it returns such as int, float, double etc...

$ nano hello.c

$ gcc hello.c

$ fg 

$ a.out
Hello world