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C programming (1)

 

INTEGER NUMBERS

short int

int

long int

 

REAL NUMBERS

float :precision 6 decimal digits, maximum value 3.4x10**38, smallest value

1.17x10**(-38)

double: precision 15 decimal digits, maximum 1.79x10**308, smallest value

2.22x10(-308)

long double: precision 19 decimal digits, maximum 1.18x10**4932, smallest value

3.36x10**(-4932)

 

CHARACTER COMMAND

char

 

EXAMPLES

char destination[12];

char name[10] = "Jeannette";

char name[] = "Jeannette";

int time;

 

CONSTANTS

const char name[] = "Jeannette";

const float vat = 0.175;

const float pi = 3.14159;

 

LIBRARIES

<assert.h>

Diagnostics

<ctype.h>

Character handling

<errno.h>

Errors

<float.h>

Characteristics of floating types

<limits.h>

Sizes of Integral Types

<locate.h>

Localisation

<math.h>

Mathematics

<setjmp.h>

Non-local jumps

<signal.h>

Signal Handling

<stdarg.h>

Variable Arguments

<stddef.h>

Common definitions

<stdio.h>

Input/Output

<stdlib.h>

General Utilities

<string.h>

String handling

<time.h>

Date and time

 

OUTPUT

printf("Hello");

Symbols for printing

\a

Alert(bell)

\v

Vertical tab

\b

Backspace

\\

Backslash

\f

Form Feed

\?

Question mark

\n

New Line

\'

Single quote

\r

Carriage return

\"

Double quote

\t

Horizontal tab

 

 

 

EXAMPLES

printf("Hello\n");

Format specifications corresponding to the list of arguments after the control string:

Form type:

%width[.precision]type

The type must be one of the following:

d,i

Decimal integer

o

Unsigned octal

x,X

Unsigned hexadecimal

u

Unsigned decimal integer

c

Single-character

s

String

f

Floating-point number

e,E

Floating point number in exponential format

g,G

Floating point number in either fixed decimal or exponential format, whichever is more compact

 

EXAMPLES

printf("alpha = %5d\n", alpha); alpha=31678

printf("beta = %-10.4f", beta); beta=1.2345

printf("Cash amount\t\t%5.2f\n", cash);

Cash amount 20.00

 

INPUT

scanf("%d", &alpha);

scanf("%10f", &beta);

scanf("%u%u%u", &day, &month, %year);

 

CHARACTER INPUT/OUTPUT

The routine getchar() will enable a single character to be input at the keyboard and stored as an integer. So :

char character;

int code;

printf("Input a single character");

code = getchar();

character = (char) code;

How to overcome a problem like this:

int price;

char nadia[10];

printf("Enter your name");

gets(nadia);

printf("Price of %s" , nadia);

scanf("%2d", &price); getchar()

 

INTEGER DIVIDED BY INTEGER ****

int distance;

int speed;

float time;

time = (float) distance / (float) speed;

 

PROGRAM FORMAT

/*

You can write whatever you want in here....

*/

 

#include <stdio.h>

main()

{

declaration of constants and variables

sequence of instructions

}

 

ARITHMETIC

+

Addition

-

Subtraction

*

Multiplication

/

Division

 

THE if STATEMENT

if (expression) statement

if (expression) statement else statement

RELATIONAL OPERATORS

OPERATOR

MEANING

OPERATOR

MEANING

>

Greater than

<=

Less than or equal to

<

Less than

!=

Not equal to

==

Equal to

&&

AND

>=

Greater than or equal to

||

OR

 

if (alpha == 2)

print("Hello");

 


 

if (beta >= 3)

printf("Good morning");

else

printf("Good night");

 

 

if ( alpha == beta)

{

A=B;

C=D;

}

else

{

A=D;

C=B;

}


if (a <= 5 && b<= 3) reply = reply -32


 

if (reply == yes && temperature < 60)

a = a+5;

else if (reply == yes && temperature <= 60)

a=a+6;

else if (reply == no && temperature <= 60)

a=a+7;

else

a=a+8;

if (C == V1)

{ E1; }

else if ( C == V2)

{ E2; }

else if (C == V3)

{ E3; }

switch (C)

{

case V1 : { E1; break; }

case V2 : { E2; break; }

case V3 : { E3; }

}

if (C == V1)

{ E1; }

else if ( C == V2)

{ E2; }

else if (C == V3)

{ E3; }

else { E4; }

switch (C)

{

case V1 : { E1; break; }

case V2 : { E2; break; }

case V3 : { E3; break; }

default : { E4; }

}

 

switch (number)

{

case 5: printf("The input number is 5"); break;

case 10: printf("The input number is 10"); break;

case 29: printf("The input number is 29"); break;

default: printf("sorry, no such number");

}

 

switch (month)

{

case 1: case 3:

number = 31; break;

case 2: case 4: {

if (year == 0)

printf("Hello");

else

a = 56;

break;

}

default: a = 76;

}

 

In a string declaration, it is not possible to assign a string literal to a string variable. A string must be copied into a variable using the routine strcpy from the <string.h> header found in the standard library.

 

Enumerating data type

An enumeration is a collection of integer values that have been given names by the programmer. All enumerated constants start with the integer value 0 unless otherwise specified with the programmer.

enum ( red, blue, green=10, yellow } colour;

C gives the values of red=0, blue=1, green=10, yellow=11. The variable colour can get only one of these four values.

The typedef command

This command enables the programmer to explicitly define new commands by using the ones that already exist. It is like having a cope of the commands with other names.

typedef long int FOUR_BYTE_INT;

FOUR_BYTE_INT x;

x is now a long int.

typedef enum {false, true} boolean;

boolean error = false;

Boolean can be either false=0 or true=1. The second command initialises boolean with the value false.

 

Example:

#include <stdio.h>

#include <string.h>

main()

{

typedef enum{false, true} boolean;

const char yes = 'Y';

const char no = 'N';

char reply;

char garment[9];

int temperature;

boolean error = false;

 

printf("What is the temperature outside today? ");

scanf("%2d", &temperature); getchar() ;

 

printf("Is it raining outside? Answer Y or N");

scanf("%c", &reply);

 

if (reply == yes)

if (temperature < 60)

strcpy(garment, "raincoat");

else

strcpy(garment, "umbrella");

else

if (reply == no)

if (temperature < 60)

strcpy(garment, "overcoat");

else

strcpy(garment, "jacket");

else

error = true;

 

if (error)

printf("DATA ERROR - reply not input as either Y or N\n");

else

printf("before you go out today take your %s\n", garment);

}

 

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