1. C Language By Sra Sontisirikit 49541212

2. Background of C language • C is high level language create in 1972 • By Brian W. C. Kernighan & Dennis M. Ritchie • Based on two languages : BCPL and B Brian Kernighan Dennis Ritchie

3. Goals and Purpose • Straightforward language • Provide low-level access to memory • Require minimal run-time support

4. Language Structure and Syntax A C program basically has the following form: • Preprocessor Commands The preprocessor is a program that is invoked by the compiler to process code before compilation. • Type definitions • Function prototypes -- declare function types and variables passed to function. • Variables • Functions

5. type function_name (parameters) { local variables C Statements }

6. Language Structure and Syntax This is simple program that will print a String#include <stdio.h> int main(){printf("This is my first program in C.\n"); return 0; }

7. #include <stdio.h> This line call "Compiler Directives" to command program to compile file "stdio.h", that use for call method printf. • int main() The line int main() declares the main function. Every C program must have a function named main somewhere in the code. • {...} The { and } symbols mark the beginning and end of a block of code. In this case, they are for the main method to contain the statements. • printf(...) The printf statement is called the format string. It can contain a string such as "This is my first program in C.". And the "/n" symbol is to move the print position to the next line. • return 0; This line means the function is ended.

8. Variables

9. Features of the language • Small size • Extensive use of function calls • Loose typing -- unlike PASCAL • Structured language • Low level programming readily available • Pointer implementation - extensive use of pointers for memory, array, structures and functions.