Algorithms and Programming Chapter 2: Overview of C ... · Chapter 2: Overview of C General form of a C program C language elements Maltepe University Computer Engineering Department

Chapter 2: Overview of C

General form of a C program

C language elements

Maltepe University

Computer Engineering Department

Algorithms and Programming

http://www.ee.hacettepe.edu.tr/~alkar/ELE108

(Info only)

(Info only)

(Info only)

See L3_7_skeleton.C as a template for C programs.

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Statement Comments - Do/Don’t

Say why, don’t paraphrase the code:

NO: /* subtract one from sheep */

sheep = sheep - 1;

YES: /* account for the sheep that

the big bad wolf just ate.*/

sheep = sheep - 1;

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See L3_29_C Dilinde Kullanılan Karakter Tipleri.docx and L3_29_C Data Types_Range

of values.docx for more details.

Also see programs L3_29_DataTypesSizeRanges.c and L3_29_StackOverFlow.c

Not 5 but 5.0

Not “A”

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Memory example

Variable declarations in C int i = 12; double gasPrice = 1.799; char bang = ‘!’;

Picture:

i

gasPrice

bang

12

1.799

‘!’

(int)

(double)

(char)

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printf( "format-string", expression1, expression2 ... );

See L3_34_Printf_YerTutucuÖrnek.JPG

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Escape Sequences (Character Constants)

Escape Sequence Represents

\a Bell (alert)

\b Backspace

\f Formfeed

\n New line

\r Carriage return

\t Horizontal tab

\v Vertical tab

\' Single quotation mark

\ " Double quotation mark

\\ Backslash

\? Literal question mark

\ ooo ASCII character in

octal notation

\x hh ASCII character in

hexadecimal notation

http://msdn.microsoft.com/en-us/library/h21280bw(v=vs.80).aspx

See L3_36_YertutucuOrnek.c 36

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Examples

This code:

int x=3;

printf("%d is a prime number.\n", 43);

printf("43 plus 59 in decimal is %d.\n", 43+59);

printf(“Here %s go.", “you\n”);

printf(“\nA character %c a decimal number%d%s", ‘T’,x,”…”);

Produces this output:

43 is a prime number.

43 plus 59 in decimal is 102.

Here you

go.

A character T a decimal number 3... 38

See L3_38_printf1.c, L3_38_printf2.c

• %10.2f _ _ _ _ 1 2 3 . 5 5 double

• %10.4f _ _ 1 2 3 . 5 5 0 0

• %.2f 1 2 3 . 5 5

• %10d _ _ _ _ _ _ _ 4 7 5 int

• %-10d 4 7 5 _ _ _ _ _ _ _

• %10c _ _ _ _ _ _ _ _ _ a char

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Output Format Examples

See L3_39_BiçimliÇıktı.c program

Do NOT forget & sign! 40

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space (‘ ’), tab (‘\t’), newline (‘\n’) are “whitespace”

Whitespace is skipped by scanf for int (“%d”), and double

(“%lf”)

This means the user can type spaces before a number

and they are ignored

Not skipped for char input “%c”

each character typed, including spaces, is used

Whitespace

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•Basic rule:

–% placeholders in the format must match variables

in the input list

– MUST! match one-for-one in number, order, and

type.

int studentID ;

double grade ;

scanf (“%d %lf”, &studentID , &grade ) ;

Multiple Inputs

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#include <stdio.h>

int main()

{

int x;

float y;

double z;

printf("Bir tamsayi ve iki adet de reel sayi girin:");

scanf("%d%f%lf",&x,&y,&z);

printf("x=%d y=%f z=%f",x,y,z);

return 0;

}

Sample – (See L3_44_scanf1.c)

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#include <stdio.h>

int main()

{

int x;

float y;

double z;

printf("Bir tamsayi ve iki adet de reel sayi girin:");

scanf("%d%f",&x,&y);

printf("x=%d y=%f z=%f",x,y,z);

printf("\nhafizadan aliyor kalan degerleri\n");

scanf("%lf",&z);

printf("x=%d y=%f z=%f",x,y,z);

return 0;

}

Sample – (See L3_44_scanf2.c)

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Sample – (See L3_44_scanf3.c)

#include <stdio.h>

int main()

{

int sayi;

char harf;

printf("Bir tamsayi ve bir karakter girin: ");

scanf("%d%c",&sayi,&harf);

printf("sayi=%d harf=%c=\n",sayi,harf);

printf("sayi=%d harf=%d=",sayi,harf);

return 0;

}

Karakter okumadan önce sayı okunursa hafızada kalan whitespace

karakterlerini temizlemek gerekir.

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Sample – (See L3_44_scanf4.c)

#include <stdio.h>

int main()

{

int sayi;

char harf;

printf("Bir tamsayi ve bir karakter girin: ");

scanf("%d %c",&sayi,&harf);//Karakter okumadan önce

//boşluk ekleyip hafiza temizlenir

printf("sayi=%d harf=%c",sayi,harf);

return 0;

}

See slide 10. 48

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DO

Use plenty of comments - but not too many

Use white space

Use indentation

Choose descriptive names

Use named constants

DON’T

be terse, tricky

place speed above correctness, simplicity

use “magic numbers”

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Style Summary: Clarity is Job #1

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