C Programming

Laboratory I

Introduction to C Language

/* the first program for user */#include <stdio.h>int a=0;int main(void){

printf(“Hello World\n”); return a;

}

CommentHeader fileDecaration

Program Body

Comment

Do not want to compile this section There are 2 forms

/* comment part */

// comment part used only borland C compiler

/* This is comment *//* For produce the good program, should Write comment every 10-15 line of program *///Or use line comment for Borland C

Preprocessing Directives (#)

Use for inform compiler to do something before compiling

#define #endif #error#ifndef #elif #if#include #else#ifdef#pragma #undef

#define Directive

Define word expression or command

#define <name> <value|expression>

Example #define TEN 10#define PI 3.141592654#define R 2*PI#define MUCH 3*6+5 \

-(7*3)

#include Directive

Read the according files to co-compile

#include <filename>#include “filename”

Example #include <dos.h>#include “sample.c”

Structure of module

Program, written by C consisted of modules

Main() is the principle module One program have to have one main()

Module-type module-name(argument){

a sequence of commands;}

Identifiers

Definition of all of name such as variable

1. Keywords

2. User-defined word

Auto default float register struct volatileBreak do for return switch whileCase double goto short typedefChar else if signed unionConst enum int sizeof unsignedContinue extern long static void

Rule of User-defined word

Case sensitive Character “_” Number First with Character or “_” Have to define before use Define in any command or expression Don’t same as KeyWord

Type of Identifiers

Global Identifiers : define external a set of command

Local Identifiers : define internal a set of command

A

B

DATA TYPE

DATA TYPE Size

char -128 to 127 1 Byte

unsigned char 0 to 255 1 Byte

int -32768 to 32767 2 Byte

unsigned int 0 to 65535 2 Byte

long -2147483648 to 2147483647 4 Byte

unsigned long 0 to 4 Byte

float -3.4E+38 to 3.4E+38 4 Byte

double 1.7E+308 8 Byte

void No-specified / No-Value return -

constant

Integer constant

Floating constant

Character constant

Interger : 5 10 -12 75Long int : 100000LHex Form : 0x7a 0xfe 0x100

0.0e0 : 3.2e50.0E0 : 3.4E-8

‘A’ ‘b’ ‘#’

Variables

Name for calling the value in memory Format for define variables

<DATA-TYPE> <VAR-NAME>[,<VAR-NAME>];

Examplechar a,b,c;unsigned int d;

Expressions

Expressions in form

operand1 operator operand2

Operator Meaning Expression Result

+ Add 7 + 3 10

- Substract 7 – 3 4

* Multiple 7 * 3 21

/ Divide 7 / 3 2.333

% Modulate 7 % 3 1

Statements

The complete command to instruct computer to do something

Enclose with ; (semi-colon) Blank space is not important

Assignment Statements

following Form

It mean calculate expression in right side and assign in variable in left side

<Variable> = Expression;

Input & Output

Character Code String Output Statement Input Statement

Character Code

Character represent to computer in number,called ASCII Code ( American Standard Code for Information Interchange) 128 characters,7 Bits

Extended ASCII Code 128 characters for special character such as Greek-Latin character, including Thai font

Big program occurred when using more than 2 language or the language require more character such Chinese Language.

Represent enclose with ‘ and ’ (qoute symbol)

‘a’ ‘4’ ‘\0’ ‘\n’

STRING

A sequence of characters Represent enclose with “ and ” (double qoute)

“Hello world!”

Output Statement

command present string on monitor

printf(charformat[,argument]);

Exampleprintf(“Hello World!”);a = 12;

printf(“Hello! Number%d”,a);

Output Statement

Type this program

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}

Input Statement

Command get value from keyboard

scanf(char-format[,address]);

#include<stdio.h>void main(void){ int date,month,year; printf(“Please enter date in dd/mm/yy :”); printf(“date :”); scanf(“%d”,&date); printf(“month:”); scanf(“%d”,&month); printf(“year :”); scanf(“%d”,&year); printf(“Date: %.2d/%.2d/%.2d\n”,date,month,year);}

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