Update

c.md

@@ -50,23 +50,28 @@ TODO
 
 ## Basics
 
-A simple program in C looks like e.g. like this:
+This is a quick overview, for a more in depth tutorial see [C tutorial](c_tutorial.md).
+
+A simple program in C that writes "welcome to C" looks like this:
 
 ```
-TODO
+#include <stdio.h> // standard I/O library
+
+int main(void)
+{
+  // this is the main program
+    
+  puts("welcome to C");
+
+  return 0; // end with success
+}
 ```
 
+You can simply paste this code into a file which you name e.g. `program.c`, then you can compile the program from command line like this:
 
-You can quickly compile the program from command line like this:
+`gcc -o program program.c`
 
-`gcc -o my_program my_program.c`
-
-You can replace `gcc` with other compilers (e.g. `clang`, `tcc`, `g++` etc.), they mostly understand the same flags. Some important flags you may want to add:
-
-- `-O3`: optimize for program speed, greatly speeds up your program (you can also use less aggressive `-O2` and `-O1`)
-- `-Os`: optimize for smaller program size
-- `-g`: include debug info, you want this so that debuggers can point to your source code
-- `-std=c99`: use the C99 standard
+Then if you run the program from command line (`./program` on Unix like systems) you should see the message.
 
 ## Cheatsheet