1. CSE 2541 – Advanced C Programming

2. Course info Prereq – CSE 2221 or CSE 222 Co-req – CSE 2231 Website http://www.cse.ohio-state.edu/~shir/cse-2451/

3. Brief history of C 1970’s – Unix – C, from BCPL (Thompson and Ritchie) C programming Language – Widely used like the others: Fortran, Pascal – Main form of language for system programming – Available on any machine with C compiler and library

4. Why C? Popular language – Operating systems (Win, Linux, FreeBSD) – Web servers (Apache) – Web browsers (Fox) – Mail servers (sendmail, postfix) – DNS servers (bind) – Graphics card programming (OpenCL) Programming language rankings Why? – Performance – Portability – Familiar to programmers

5. Why C? Compared to assembly language – Abstracts the hardware view (registers, memory, call stacks), making code portable and easier – Provides variables, functions, arrays, complex arithmetic, Boolean expressions Compared to other high-level languages – Maps almost directly into hardware instructions, making optimization easier – Provides a minimal set of abstractions compared to other HLLs – Like other HLLs, makes complex programming simpler (at the expense of efficiency)

6. C characteristics "C" because many features came from earlier language “B“ – Reduced form of Basic Combined Programming Language, 1966 Block structured – Blocks are denoted { } Many utility functions provided in libraries – Libc, libpthread, libm – Nowhere near the functionality of other runtime environments Some major C features – Functions, Structures, Types – Pointers – direct access to memory space

7. C vs. Java Speed Portability Object orientation

8. C vs. Java Pointers to memory Platform dependent types Programmer allocated memory Declare variables at start of block References to objects Types have well defined sizes Automatic garbage collection Declare variable anywhere

9. Hello World – code /* Hello World! */ #include int main() { printf(“Hello World!\n”); return 0; }

10. C compilation model

11. Hello World – walkthrough C program: hello.c – emacs, vi, vim, pico, joe … – Plaintext only Preprocessing and Compiling: hello.s, assembly code – cc -S hello.c Assembler: hello.o, a binary file – cc -c hello.s Linking: a.out or hello, an executable file – cc hello.o – cc -o hello hello.o Loading (dynamical linking) and execution:./hello –./a.out –./hello

12. Hello World – content breakdown Comment Preprocessor directive Function definition Output statement Return clause

13. #include int main() { int first, second, add; float divide; printf("Enter two integers\n"); scanf("%d%d", &first, &second); add = first + second; divide = first / (float)second; printf("Sum = %d\n",add); printf("Division = %.2f\n",divide); return 0; } Second Example

14. Second example – content breakdown Variables Function calls – Input – Output Operators Typecasting