??as??p?s? t?? C (

1
??as??p?s? t?? C (µ???d?? a????s??)

• ?st???a
• ??µ? ?a? St???e?a C p????aµµat??
• S??ta?? ?a? S?µas??????a
• ??a??s? s?µpe??f??a? µe Trace Table

2
?st???a C

• ??apt?????e a??e? 1970
• Kernighan and Ritchie The C Programming
  Language, 1978
• G?a Systems OS ?a? µeta???t?ste?
• p??? p?? e??e?a? ???s?? s?µe?a
• ???t?p? ANSI C (1988)

3
?a??de??µa ?????aµµa
/ paradeigma programma / include
ltstdio.hgt void main() printf(First C
Program\n)
E?a???? ?????aµµat??
First C Program gt
4
S?µas??????a (semantics)
S????a
/ paradeigma programma /
?d???e? p??? p??epe?e??ast? ??a s?µpe??????
ß?ß????????
include ltstdio.hgt
void main()
???sµ?? s??a?t?s?? main ?a?e p????aµµa e?e? main
?????e? pe??e???? (s?µa) e?t??e? t?? s??a?t?s??
main
printf(First C Program\n)
??t??? ?a?e? s??a?t?s? ß?ß???????? ??a e?a???? -
pa?aµet??? a???????a ?a?a?t????
5
/ programma poy ypologizei athroisma dyo
akeraiwn arithmwn / include ltstdio.hgt void mai
n() int numbera, numberb / inputs/ int
sum printf(Enter two numbers
) scanf(dd,numbera, numberb) sum
numbera numberb printf(The sum of d and d
is d\n, numbera, numberb, sum)
6
??a????
Enter two numbers
34 -12
The sum of 34 and -12 is 22
gt
foo
Enter two numbers
3 0
The sum of 3 and 0 is 3
gt
7
/ programma poy ypologizei athroisma dyo
akeraiwn arithmwn /
S????a
??ß??????? ??a ?/?
include ltstdio.hgt
void main()
S??a?t?s? main
????se?? a?e?a?e? µetaß??te?
int numbera, numberb / inputs/ int sum
printf(Enter two numbers ) scanf(dd,nu
mbera, numberb)
??t??e? µe s??a?t?se?? stdio ??s?d??
ded?µe??? µetaß??te? ep??ta? ap? t?? te?est?
d?e????s??
sum numbera numberb
e?t??? te?est?? (operator) p??s?es?? d?ad????
te?est?? d?? te?esta???? (operands) te?est??
a?a?es??
printf(The sum of d and d is
d\n, numbera, numberb, sum)
??t??? µe s??a?t?s? stdio ??a???? ded?µe???
8
Ge???e? ?a?at???se??

• Kata???ta )
• ?a? ta d?? e???? main
• ??e? ?? e?t??e? ?a? d???se?? te?e?????? µe
• ???s? s??a?t?se?? stdio (printf, scanf)
• printf e?t?p??e?
• \n ???e? t?? d??µea (cursor) st?? ep?µe?? ??aµµ?
• scanf d?aßa?e? ap? t?? ???st?
• pa???e? d?e????s? µetaß??t??, pa???e? t?µ?

9
??µ? p????aµµat?? C
/ s????a / / ?d???e? st?? p??epe?e??ast?
/ / d???se?? sta?e???, µetaß??t??/ /
???sµ?? s??a?t?se?? / / ???sµ?? s??a?t?s??
main /
10
??µ? p????aµµat?? C (s??.)

• ?? p????aµµa µp??e? ?a ap?te?e?ta? ap? e?a ?
  pe??ss?te?a a??e?a
• C e??a? d?ad??as?a?? ???ssa
• s??a?t?se?? (functions)
• µetaß??te? (variables)

11
S????a

• S??ta?? ?e?????? µe / ?a? te?e?????? µe /
• ?aµµ?a s?µas?a a??a p??? s?µa?t??? µe??? e???
  p????aµµat?? (te?µ????s?)

/ auto einai ena syntaktika ortho sxolio/
/ kai auto einai syntaktika ortho /
12
S????a (s??.)
/ auto ti einai / /auto???
/ / lathos sxolio / giati
/ / einai lathos??? /
13
include

• ?d???a st?? p??epe?e??ast? ??a e?s?µat?s?
  ß?ß????????
• ??a ß?ß??????? (library ? header file) e??a? µ?a
  s?????? ???s?µ?? s??a?t?se?? ?a? sta?e???
• S??ta?? include ltheader filegt
• p? include ltstdio.hgt

14
include (s??.)

• ??s?µat?s? ep?t?epe? t?? ???s? s??a?t?se?? ?a?
  sta?e??? µ?a? ß?ß????????
• p? ? ß?ß??????? stdio pe????e?, a??µesa se ???a,
  t?? s??a?t?se?? printf, ??a e?t?p?s? p????f?????,
  ?a? scanf, ??a e?sd??? p????f?????
• ???e? d?ata?e? st?? p??e?e??ast?
• define, ifdef, if, else, endif, undef

15
???µata st?? C

• G?a sta?e?e?, µetaß??te?, s??a?t?se??
• ? C e??a? CASE SENSITIVE, ?efa?a?a ?a? µ???a
  ??aµµata e??a? d?af??et??a
• foo ?a? FOO e??a? d?? d?af??et??a ???µata
• ???s?µ?p??ata? a?t?epe????µat??a ???µata
• ???µata de? p?epe? ?a ???s?µ?p????? desµe?µe?e?
  ?e?e??

16
?e?µesµ??e? ???e??(Reserved Words)

• ?e?e?? µe e?d??? s?µµas?a ??a t?? C. ?e? p?epe?
  ?a ??????ta? ?a?a sa? ???µata

17
S??ta?? ???µat??
p? metavliti rectangle_area _index_123
1variable super se tria meroi
L letters a-z A-Z N numbers 0-9 _ underscore
18
S?µµas?a ?etaß??t??

• ?p????e?s? ?a? a?a???s? t?µ??
• ?a?e µetaß??t? e?e?
• t?p?
• ßas???? int, char, float, double
• µe?e??? 4?, 1?, 4?, 8? (?a?e ???e??da 1
  Byte)
• (s?µß?????) ???µa
• t? ???µa a?t?st???e? se s???e???µe?? d?e????s?
  st?? µ??µ?
• t?µ?

??a?tata? ap? t? ?e?t??????? s?st?µa
19
S?µas?a ?etaß??t??
???µa (d?e????s?)
t?p??
t?µ?
int count
0 ... ...
count 137
98760060
count count 142
foo(count)
??e????s? t?? count
t?p?? d?e????s?? ???µa?eta? de??t?? (pointer)
p? int deikths
20
S?µas?a ?etaß??t?? (s??.)

• ??epe? ?a d????eta? p??? ???s?µ?p????e?
• ?a? ß??s?eta? sta a??ste?a te?est? a?a?es?? ?
  t?µ? t?? ap?te?esµat?? t?? e?f?as?? (expression)
  sta de??a t?? ap????e?eta? st?? d?e????s? t??
  µetaß??t??
  ?????? ???s?µ?p??e?ta? ? t?µ? t?? µetaß??t??

21
????s? ?etaß??t?? (variable)
char letter int count, sum float area, double
volume int index cost double charge float
angle, income
22
????s? Sta?e?a? (constant)
????s? sta?e?a?
???µa
define
t?µ?
define PI 3.1453 define YES 1 define
NO 1 define TRUE 1 define PISQUARE
PIPI define ERROR_SPACE_MESSAGE errorrun out
of space
23
S?µas?a Sta?e?a?

• Sta?e?e? e????
• t?µ?
• ???µa ??? ?µ?? d?e????s?
• µeta???t?st?? a?t??a??sta t? ???µa µe t?? t?µ?
• ??e??????e?
• t??p?p???se??
• d?aßasµa e??? p????aµµat?? (PI ? 3.1453)

24
??p?? ?ed?µ????

• ??a? t?p?? ded?µ???? e??a? ??a s????? t?µ?? ?a?
  ??a s????? ?e?t??????? (p???e??) p?? µp????? ?a
  efa?µ?st??? se a?t?? t?? t?µ??
• ßas???? (char , int , float, double)
• s???et?? (arrays, unions, structs)

25
char (?a?a?t??a?)

• ??apa??st? at?µ????? ?a?a?t??e? A-Z, a-z, 0-9,
  !_at_, e?d??? s?µß??a \n, ?t?
• ?e?e??? 1 byte. ??se? µ??ad??e? t?µe??
• ??????e?t???? t?µ?? es???e???ta? se ap?st??f???,
  p.?. ???, ?a?, ?9?, ???, ? ?, ??, ?\n?, ?\??,
  ?t?
• ?? ap?st??f?? de? ??e?????ta? ?ta? e?s????ta?
  ?a?a?t??e?

26
int (a???a???)

• ??apa??st? a?e?a???? a???µ???
• ?e?e??? 4 bytes, ped?? t?µ?? -231-1.. 231-1
• ?a?ade??µata ??????e?t???? t?µ??
• -2189456 0 50 24562 3245 13576313
• ????e?? p??s?es? (), afa??es? (-),
  p???ap?as?asµ?? (), d?a??es? (/), ?p????p? (),
  ?t?

27
float (????t?? ?p?d?ast???? µ???? a???ße?a?)

• ??apa??st? t??? p?a?µat????? a???µ???
• ?e?e??? 4 bytes, 1x1037,1x10-37
• ????e?? p??s?es? (), afa??es? (-),
  p???ap?as?asµ?? (), d?a??es? (/)
• S?µe????af?a ??a ??????e?t???? t?µ??
• 1.258 ? 106 1258000.0 1.258e6 1.258E6
• 8.9 x 10-4 0.00089 8.9e-4 8.9e-4 .00089

28
double (????t?? ?p?d?ast???? d?p??? a???ße?a?)

• ?d??? t?p?? µe float a??a µe µe?a??te?? a???ße?a
• ?e?e??? 8 bytes

29
S??a?t?se?? (functions)

• ?a?e C p????aµµa ap?te?e?ta? ap? µ?a ?
  pe??s?te?e? s??a?t?se??
• ?a?e p????aµµa e?e? µ?a s??a?t?s? main
• ??te?es?? ?e???a ap? t?? s??a?t?s? main
• S??a?t?se?? ?a????ta? (called) ?a? ep?st?ef???
  (return)
• ?ta? ?a????ta? pa?????? pa?aµet????

30
S??ta??
ltt?p?? ep?st??f??gt lt???µa_S??a?t?s??gt(lt??sta
pa?aµet???gt) / a??? t?? s??a?t?s?? / /
d???se?? µetaß??t?? / / e?t??e? / return
lte?f?as?gt / te??? t?? s??a?t?s?? /
31
S??a?t?se?? (s??.)
int display() printf(First C
Program\n) return(0)
S??a?t?s? de? pa???e? pa?aµet????
?p?st?efe? t?? t?µ? 0 0 e??a? int
32
S??a?t?se?? (s??.)
S??a?t?s? pa???e? d?? pa?aµet????
int compute_sum(int a, int b) int sum sum
a b return sum
?p?st?efe? t?? t?µ? sum p?? e??a? int
33
include ltstdio.hgt int compute_sum(int a, int
b) int sum sum a b return sum void
main() int numbera, numberb / inputs/ int
sum printf(Enter two numbers
) scanf(dd,numbera, numberb) sum
compute_sum(numbera, numberb) printf(The sum
of d and d is d\n, numbera, numberb, sum)
34
1? ?s??s?

• ???a?te t? p????aµµa p?? ?p??????e? eµßad?
  ?????????? ?a ?p??????e? ???? e??? ste?e??.
• ?µe?oµ???a ?a??d?s?? 14/2