C Language By Sra Sontisirikit 49541212

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

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

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

type function_name (parameters) { local variables   C Statements   }

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; }

#include <stdio.h> int main() {...} printf(...) 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.

Variables

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.