??(Function)???

1
Introduction to the C Programming Language

• ??(Function)???

2
Fucntion

• (?????????)

3
??Function (??)?

• ????(Function)?
• ???????????,??coding ??
• ?????????,??????
• ?????????????,?????????
• ?????????,???????????function, ?????????????
• ??????????(???,??????)
• ????
• ??????,????????
• ???????,?????????

4
???????

• ?????????
• /?????main()???, ??????, ????/
• ????? function_name (????1,????2)

5
Function????(1/2)

• ????
• ??????? ????(??????? ????, ??????? ???? )
• statements /????/
• return ??? /??????/

6
Function????(2/2)

• ????1 (????)
• void function_name (???? ??1,???? ??2)
• parameters declarations /??????/
• statements /????/
• ????2 (???)
• ???? function_name (???? ??1,???? ??2)
• parameters declarations /??????/
• statements /????/
• return ???

7
Example 1a

• ??????,????
• includeltstdio.hgt
• void p(char sn ) /????,????void?????,????ch
  ar??/
• int main(void) /???/
• char num10
• printf("?????")
• scanf("s",num)
• p(num) /??p??/
• printf("\n")
• system("pause")
• void p(char sn ) /p??/
• printf("\n\n????? s",sn)

?????
?????
8
Example 1b

• ??????,????
• includeltstdio.hgt
• void p(char ) /????,????void?????,????char??
  /
• int main(void) /???/
• char num10
• printf("?????")
• scanf("s",num)
• p(num) /??p??/
• printf("\n")
• system("pause")
• void p(char num )
• printf("\n\n????? s",num)

/p???num ??????num ????/
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Example 2
?? ?????,???????,?????????????,????. include
ltstdio.hgt int add(int,int)                      
     /????,???? int???int??,????int?? / void
show(int)                         
/????,???? void?????,????int?? /  void main()
int nNum1 5 , nNum2 5 , nSum
nSum add(nNum1,nNum2)       /?add(nNum1,nNum2)
?return??nSum / show(nSum)                  
               /?nSum??show?? /    
/?????nNum1,nNum2,????int?nData1 nNum1, nNum2
nData2 /  int add(int nData1,int
nData2)        return (nData1
nData2)        /??nData1 nData2???? /
  /????nSum,????int nData,?nData nSum
/  void show(int nData) printf("The Anser
is d" , nData)
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??????????

• ?????
• ?????

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Function????

• ??????????????.
• ????????,?????.
• ????????????.
• ?????????????????????????, ?????????,???????,
  ????????.
• ?????????, ????????????,????? return (???)
• return ????
• ???????,????????
• return ????????????????,?????????, ?????????.

12
???

• return() ???????
• ???????????
• ?return()??????????????????

13
??
14
???????

• ?????(Global variable) ????????????,
  ???????????????.
• ?????(Local variable) ??????????????????,
  ???????????. ?????????????, ?????????????.

includeltstdio.hgt /????,?????/ ???? ????
/????/ int main( ) ???? /????/ return
0 /???/
15
???????

• C????????? auto, extern, static, register
• ????auto ?????????????.
• ????(Static variable) ????????, ??????????,
  ???????????????????.
• ????(Extern variable) ???????????????????????,
  ???????.
• ?????? ????????????????, ??????????????.
• ?????(Register variable)???????????, ???????2?,
  ???2?, ??????????????auto????.

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??? ?????????
includeltstdio.hgt includeltstdlib.hgt int
sum(void) void main(void) int i /????/
for (i1 ilt3 i) printf("dth time
d \n", i, sum()) system("pause")
int sum(void) int x0 /????/ x
return(x)
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??? ?????????
includeltstdio.hgt includeltstdlib.hgt void main()
int sum(void) int i /????/ for
(i1 ilt3 i) printf("dth time d \n",
i, sum()) system("pause") int sum(void)
static int x0 x return(x)
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??? ?????????
includeltstdio.hgt includeltstdlib.hgt int
sum(void) int x0 /????/ void main(void)
int i /????/ x for (i1 ilt3
i) printf("dth time d \n", i,
sum()) system("pause") int
sum(void) x return(x)