C String

1
C String
C Language Computer
Programming
2
Basic of String in C Language

• String ?????? C ????????? Array ??? Character
  ?????????????????? ???????????????????????? Array
  ??? Character ??????? null Character(\0)
  ?????????????????????

char string20Initial Message
0 1 4 9 14 15 19
I n i t i a l M e s s a g e \0 ? ? ? ?

• ????????????????? null character(\0)
  ????????????
• ???????????????????? 15 ????????

3
Basic of String in C Language

• String vs. Array of char

String char color blue char color
b, l, u, e,\0 Array of char char
color b, l, u, e
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Basic of String in C Language

• ??????????????? String ???????????? char

char month January
????? array ???? 5
char monthPtr January
??????????? pointer ??????????? string January
?????????????
5
???????????????????????????? String

• ???????????????????????????????? String
• char msg10 Computer
• char msg10 C,o,m,p,u,t,e,r,
  \0
• ??????????????????????????????????????????
  String
• char msg Computer
• char msg Computer"
• char msg C,o,m,p.u,t,e,r,
  \0

6
??? Copy String

• char str110Computer
• char str230
• str2str1
• str2Computer

?????????????????????????? String
...??????????????????????
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String Input Functions

• scanf

scanf( s, msg )
scanf ???????????????????? user
?????????????????????? ??????????? space,
newline ???? end-of-file character
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String Input Functions

• ?????????????????????????????????????????????????
  ????? array ???????????? ???????????????

char msg10 printf(Enter Message
) scanf(s, msg)
?
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String Input Functions

• ?????????????????????????????????????????????????
  ?????????? ??????????????????????????????????????

char msg10 printf(Enter Massage
) scanf(9s, msg)
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String Input Functions

• Edit set ( ) ??? ????????????????????????????
  ????????????????? string ??? scanf
  ????????????????????????????????????????????????
  ??? edit set ????????
• ??. ?????????????? ???????????? ????????

char msg10 printf(Enter money
) scanf(91234567890,.s,msg)
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String Input Functions

• ????????????? Edit set ( )
  ????????????????????????????????? ???????????
  ?????????????? ( ) ????????????
  ?????????????????????????????? ?????? newline
• ??????????? scanf ????????????????????????
  newline character ???????????

char msg100 printf(Enter message
) scanf(81\ns,msg)
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String Output Functions

• printf
• ?????????????????????????? string

printf( s, msg )
printf( flagprecisions, string?????????? )
Left-justify
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String Output Functions

• printf(30s,Computer)
• Output
• printf(-30s,Computer)
• Output

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String Output Functions

• printf(-20.15s,12345678901234567890)
• Output

?????????????? 20 ??????? ??????????? 15 ????????
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Standard Input/Output Library Functions
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char gets (char s)

• includeltstdio.hgt
• void main()
• char name20
• char question20 What is your name?
• puts(question)
• gets(name)
• printf(You are s\n, name)

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char gets (char s)
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int puts(const char s)
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String Library Functions
include ltstring.hgt
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String Length
int strlen( const char string )

• strlen ?????? ??????????????????? ????
  ???????????????????? ????????? null character
• ???????????????????????? ?????????????

21
String Length

• includeltstdio.hgt
• includeltstring.hgt
• void main()
• char buff20
• int num
• strcpy(buff,What happen?)
• num strlen(buff)
• printf(String contains d character,num)

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String Length

• includeltstdio.hgt
• includeltstring.hgt
• void main()
• char buff20
• strcpy(buff,What happen?)
• printf(String contains d character,
  strlen(buff))

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?????????????? strlen
include ltstdio.hgt include ltconio.hgt include
ltmalloc.hgt include ltstring.hgt void main(void)
char message int len
clrscr() message malloc(sizeof(char)256)
if(message ! NULL)
printf("Enter string ")
gets(message) len strlen(message)
printf("String length is d", len)
getch() else
printf("Out of Memory\n")
free(message)
?????????????????
Enter string Good Afternoon String length is 14