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