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
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>
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
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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.