5 2. string processing
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![3
The End-of-String Sentinel 0
String 覦覯
3蠍襯 ロ讌襷, れ襦 4bytes螳 .
char word[100];
word[0] = a;
word[1] = b;
word[2] = c;
word[3] = 0; /* string 襯 null char 曙*/](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-3-320.jpg)
![4
Initialization of Strings
Use array name
String process襯 char array襯
[Ex] char word[4] = abc;
[Ex] char word[4] = {a, b, c, 0 };
[Ex] char word[] = {a, b, c, 0 };
[Ex] char word[] = abc; compiler 朱
4 char襯 array](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-4-320.jpg)
![5
Displaying String and characters
printf()
String豢レ 伎 %s 襯
豢レ 炎概企 豢ル 蠍 覦, 蠏碁讌
朱 -1 覦
[Ex] int nchars;
char p[ ] = Hello! the world;
nchars = printf(%s, p);
printf(nnum of chars=%dn, nchars);
Hello! the world
num of chars = 16](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-5-320.jpg)
![6
Displaying String and characters
puts()
printf()覲企 fast, simple
String 豢 , next line朱 企
int puts(char *str); /*function prototype */
return
- no. of chars written if successful
- EOF(-1) if not
[Ex] char p[ ] = Hi !!;
puts(p);
puts(Hello!!); Hi !!
Hello!!](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-6-320.jpg)
![8
Reading Strings from the KB
[Ex] char name[80];
scanf(%s, name); /* name <- SKKU */
SKKU Univ.
[Ex] char name[80];
scanf(%3s, name); /* name <= C-P */
scanf(%8s, name); /* name <= rogram */
C-Program is
White space 蟾讌 read
3螳 char襯 read](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-8-320.jpg)
![10
Reading Strings from the KB
[Ex] char data[81], *P;
while( gets(data) != NULL) {
printf(%sn, data);
}
or while(gets(data) != 0)
^D襯 ロ 蟾讌 line襦
read 蠏碁襦 覃伎 豢
program
<blank line> 轟
<[ctrl] + D> 譬襭](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-10-320.jpg)
![11
Reading Strings from the KB
char a[5], b[4]=1234;
scanf(%s, a);
printf( %s %sn, a, b ) ;
Array蠍磯慨 襷 覓語襯 ロ 蟆曙
abcde襯 ロ覃 豢 螳?](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-11-320.jpg)
![12
String-Handling Functions
String Assign
[Ex] char str1[10] = abc, str2[10];
str1 = 123 ;
str2 = str1 ;
OK?? Why not??](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-12-320.jpg)
![13
String-Handling Functions
char *strcpy(char *s1, const char *s2);
s1 s2 覓語伎 伎 覲旧
Return 螳 s1 譯殊螳
s1 覓語伎 ロ 豢覿 覃覈襴襯 覲危伎
[Ex] char str1[10] = abc, str2[10];
strcpy( str1, abc ) ;
strcpy( str2, str1 ) ;](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-13-320.jpg)
![14
String-Handling Functions
String 觜蟲
[Ex] char str1[10], str2[10];
scanf( %s, str1 ) ;
scanf( %s, str2 ) ;
if( str1 == str2 ) printf( Same!!n ) ;
OK?? Why not??](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-14-320.jpg)
![15
String-Handling Functions
int strcmp(const char *s1, const char *s2);
string 蟲燕 char ascii code螳 觜蟲
return value < 0 : s1 s2 覲企 ASCII 螳
return value = 0 : s1 螻 s2螳 螳
return value > 0 : s1 s2 覲企 ASCII 螳
[Ex]
#include <string.h>
char str1[10], str2[10];
scanf( %s, str1 ) ;
scanf( %s, str2 ) ;
if( strcmp(str1,str2) == 0 ) printf( Same!!n ) ;](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-15-320.jpg)
![16
String-Handling Functions
String Length
覈 蠍螳 str1 蟾?
[Ex] char str1[10] ;
scanf( %s, str1 ) ;
[Ex] char str1[10] ;
int length ;
scanf( %s, str1 ) ;
for( length = 0 ; str[length] != NULL ; length++ ) ;
printf( The length of string: %dn, length ) ;](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-16-320.jpg)
![17
String-Handling Functions
int strlen(const char *s1);
String 蠍語企ゼ return
[Ex] char str1[10] ;
int length ;
scanf( %s, str1 ) ;
printf( The length of string: %dn, strlen(str1) ) ;](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-17-320.jpg)
![19
String-Handling Functions
char *strcat(char *s1, const char *s2);
s1 覓語 れ s2 覓語伎 豢螳
Return螳 s1
s1 覓語伎 ロ 豢覿 覃覈襴襯 覲危伎
char str1[10]="1234";
char str2[10]="abcd";
strcat(str1, str2);
printf(%s, %sn", str1, str2);
strcat(str2, efgh ) ;
printf(%sn", str2);](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-19-320.jpg)
![20
String-Handling Functions
char* strchr(const char *s1, char c1);
s1 覓語伎 螳 襾殊 覓語 c1 pointer襯
return
c1 企 覓語螳 蟆曙 null pointer襯 return
[Ex] char str[10] ;
scanf( %s, str ) ;
if( strchr(str, e ) != NULL )
printf( e is foundn );
else
printf( e is not foundn ) ;](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-20-320.jpg)
![21
String-Handling Functions
char* strstr(const char *s1, char* s2);
strchr螻 讌襷 覓語 sub-String search
蟆曙 null pointer襯 return
[Ex] char str[10] ;
scanf( %s, str ) ;
if( strchr(str, ) != NULL )
printf( hi is foundn );
else
printf( hi is not foundn ) ;](https://image.slidesharecdn.com/5-2-140406045922-phpapp01/85/5-2-string-processing-21-320.jpg)
5 2. string processing
- 2. 2 Preview String String : 朱 charactersる 蟲 C String char one-dimensional array襦 String 覦 襷 襷讌襷 null 覓語 0螳 伎 C String process襯 螳讌 Built-in Functions 螻
- 3. 3 The End-of-String Sentinel 0 String 覦覯 3蠍襯 ロ讌襷, れ襦 4bytes螳 . char word[100]; word[0] = a; word[1] = b; word[2] = c; word[3] = 0; /* string 襯 null char 曙*/
- 4. 4 Initialization of Strings Use array name String process襯 char array襯 [Ex] char word[4] = abc; [Ex] char word[4] = {a, b, c, 0 }; [Ex] char word[] = {a, b, c, 0 }; [Ex] char word[] = abc; compiler 朱 4 char襯 array
- 5. 5 Displaying String and characters printf() String豢レ 伎 %s 襯 豢レ 炎概企 豢ル 蠍 覦, 蠏碁讌 朱 -1 覦 [Ex] int nchars; char p[ ] = Hello! the world; nchars = printf(%s, p); printf(nnum of chars=%dn, nchars); Hello! the world num of chars = 16
- 6. 6 Displaying String and characters puts() printf()覲企 fast, simple String 豢 , next line朱 企 int puts(char *str); /*function prototype */ return - no. of chars written if successful - EOF(-1) if not [Ex] char p[ ] = Hi !!; puts(p); puts(Hello!!); Hi !! Hello!!
- 7. 7 Reading Strings from the KB scanf() %s : next white space char 蟾讌 read %ns : n螳 chars 襯 read, 蠏 white space螳 り 覃 white space蟾讌襯 read int scanf(char *format, argument_list); return - no. of successfully matched and input items - 0 if not
- 8. 8 Reading Strings from the KB [Ex] char name[80]; scanf(%s, name); /* name <- SKKU */ SKKU Univ. [Ex] char name[80]; scanf(%3s, name); /* name <= C-P */ scanf(%8s, name); /* name <= rogram */ C-Program is White space 蟾讌 read 3螳 char襯 read
- 9. 9 Reading Strings from the KB gets() KB襦覿 n蟾讌, 讀 line襦 read n 0襦 convert string ル. char* gets(char *format); return - the address of the string - NULL if EOF (end-of-file) scanf()襯 牛 String 覦 蟆曙: white space skip朱 white space read 覿螳. Line 襦 string 覦 .
- 10. 10 Reading Strings from the KB [Ex] char data[81], *P; while( gets(data) != NULL) { printf(%sn, data); } or while(gets(data) != 0) ^D襯 ロ 蟾讌 line襦 read 蠏碁襦 覃伎 豢 program <blank line> 轟 <[ctrl] + D> 譬襭
- 11. 11 Reading Strings from the KB char a[5], b[4]=1234; scanf(%s, a); printf( %s %sn, a, b ) ; Array蠍磯慨 襷 覓語襯 ロ 蟆曙 abcde襯 ロ覃 豢 螳?
- 12. 12 String-Handling Functions String Assign [Ex] char str1[10] = abc, str2[10]; str1 = 123 ; str2 = str1 ; OK?? Why not??
- 13. 13 String-Handling Functions char *strcpy(char *s1, const char *s2); s1 s2 覓語伎 伎 覲旧 Return 螳 s1 譯殊螳 s1 覓語伎 ロ 豢覿 覃覈襴襯 覲危伎 [Ex] char str1[10] = abc, str2[10]; strcpy( str1, abc ) ; strcpy( str2, str1 ) ;
- 14. 14 String-Handling Functions String 觜蟲 [Ex] char str1[10], str2[10]; scanf( %s, str1 ) ; scanf( %s, str2 ) ; if( str1 == str2 ) printf( Same!!n ) ; OK?? Why not??
- 15. 15 String-Handling Functions int strcmp(const char *s1, const char *s2); string 蟲燕 char ascii code螳 觜蟲 return value < 0 : s1 s2 覲企 ASCII 螳 return value = 0 : s1 螻 s2螳 螳 return value > 0 : s1 s2 覲企 ASCII 螳 [Ex] #include <string.h> char str1[10], str2[10]; scanf( %s, str1 ) ; scanf( %s, str2 ) ; if( strcmp(str1,str2) == 0 ) printf( Same!!n ) ;
- 16. 16 String-Handling Functions String Length 覈 蠍螳 str1 蟾? [Ex] char str1[10] ; scanf( %s, str1 ) ; [Ex] char str1[10] ; int length ; scanf( %s, str1 ) ; for( length = 0 ; str[length] != NULL ; length++ ) ; printf( The length of string: %dn, length ) ;
- 17. 17 String-Handling Functions int strlen(const char *s1); String 蠍語企ゼ return [Ex] char str1[10] ; int length ; scanf( %s, str1 ) ; printf( The length of string: %dn, strlen(str1) ) ;
- 18. 18 String-Handling Functions 蠏 String strcat : string るジ string 覲旧 strchr : string 伎 譯殊伎 覓語 谿剰鍵 strstr : string 伎 譯殊伎 string 谿剰鍵
- 19. 19 String-Handling Functions char *strcat(char *s1, const char *s2); s1 覓語 れ s2 覓語伎 豢螳 Return螳 s1 s1 覓語伎 ロ 豢覿 覃覈襴襯 覲危伎 char str1[10]="1234"; char str2[10]="abcd"; strcat(str1, str2); printf(%s, %sn", str1, str2); strcat(str2, efgh ) ; printf(%sn", str2);
- 20. 20 String-Handling Functions char* strchr(const char *s1, char c1); s1 覓語伎 螳 襾殊 覓語 c1 pointer襯 return c1 企 覓語螳 蟆曙 null pointer襯 return [Ex] char str[10] ; scanf( %s, str ) ; if( strchr(str, e ) != NULL ) printf( e is foundn ); else printf( e is not foundn ) ;
- 21. 21 String-Handling Functions char* strstr(const char *s1, char* s2); strchr螻 讌襷 覓語 sub-String search 蟆曙 null pointer襯 return [Ex] char str[10] ; scanf( %s, str ) ; if( strchr(str, ) != NULL ) printf( hi is foundn ); else printf( hi is not foundn ) ;