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14. fiile io

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File I/O
2 File 豢 則 讌蠍蟾讌 襦蠏碁 豢 : Keyboard 豢: Monitor 則 襭襯 殊 曙伎 豢レ 朱 蟾? 蟲 1 80 90 70 2 80 60 40 3 60 50 70 C program 蟲 蠏 1 80 90 70 80 2 80 60 40 60 3 60 50 70 60
3 File 豢 則 殊 伎 豢 谿 企 願鍵 殊 所鍵 殊 郁鍵 蠍 fopen fscanf, fprintf, fgets, fputs, fclose
4 File Operation Function fopen() 則 fopen() 碁 file 襦蠏碁 蠍 譴觜る 覈 レ 伎 覈 殊 fopen 牛 譴觜伎 Return螳: FILE 蟲譟一牡 pointer 殊 所鍵 轟 郁鍵 fopen 覦 FILE pointer襯 牛伎 企伎 則 fopen() Syntax FILE *fopen( const char *filename, const char *mode ); file pointer襦 return disk filename file open mode
5 File Operation Function fopen() 則 fopen() 殊 襭襯 所鍵 伎 殊 譴觜 my_file.txt 所鍵覈襦 譴觜 襷 殊 朱 NULL 覦 FILE *fp ; fp = fopen(my_file.txt, r);
6 File Operation Function fopen() 則 fopen() 殊 襭襯 郁鍵 伎 殊 譴觜 my_file.txt襯 郁鍵覈襦 譴觜 襷 殊 朱 my_file.txt 焔 襷 企 my_file.txt螳 譟伎覃, 蠏 覈 伎 讌讌 FILE *fp ; fp = fopen(my_file.txt, w);
7 File Operation Function fopen() 則 fopen() 殊 襭襯 豢螳襦 郁鍵 伎 殊 譴觜 my_file.txt襯 append覈襦 譴觜 襷 殊 朱 my_file.txt 焔 襷 企 my_file.txt螳 譟伎覃, 蠍一ヾ 伎 蠏碁襦 讌螻 襦 一讌 蟆 襷讌襷 豢螳 FILE *fp ; fp = fopen(my_file.txt, a);
8 File Operation Function fopen() 則 fopen() 殊 襭襯 所 郁鍵襯 伎 殊 譴觜 my_file.txt 所鍵 郁鍵螳 覈 螳ロ 覈襦 譴觜 襷 my_file.txt 朱 NULL 覦 襷 my_file.txt 朱 open螻, my_file.txt 伎 覈 讌 所鍵 郁鍵 殊 襷 豌 豺 FILE *fp ; fp = fopen(my_file.txt, r+);
9 File Operation Function fopen() 則 fopen() 殊 襭襯 所 郁鍵襯 伎 殊 譴觜 my_file.txt 所鍵 郁鍵螳 覈 螳ロ 覈襦 譴觜 襷 my_file.txt 朱 my_file.txt螳 焔 襷 my_file.txt 朱 open覃伎, my_file.txt 伎 覈 讌讌 FILE *fp ; fp = fopen(my_file.txt, w+);
10 File Operation Function fopen() 則 fopen() 殊 襭襯 所 郁鍵襯 伎 殊 譴觜 my_file.txt 所鍵 郁鍵螳 覈 螳ロ 覈襦 譴觜 襷 my_file.txt 朱 my_file.txt螳 焔 襷 my_file.txt 朱 open螻, my_file.txt 伎 覈 讌 所鍵 郁鍵 殊 襷 襷讌襷 FILE *fp ; fp = fopen(my_file.txt, a+);
11 File pointer 則 File pointer File I/O disk file覈 file pointer襯 牛 stream 燕 . 則 FILE Type stdio.h file typedef襦 type朱 file 覲企ゼ 襦 struct type [Ex] FILE *fp; /* file pointer襦 fp */
12 File Operation Function fclose() 則 fclose() fopen朱 open 殊 覃 fclose襯 覦 殊 . 則 fclose() Syntax int fclose( FILE *stream ); open file pointer name Returns 0 : successful EOF : error (EOF is defined as 1 in stdio.h)
13 File Operation Function fopen() 則 fclose() #include <stdio.h> int main() { FILE *fp ; fp = fopen(my_file.txt, r); ... fclose( fp ) ; return 0 }
14 Formatted I/O Function fprintf() 則 fprintf() 豌襴襯 printf()覓語企. 豌 語 fopen 伎 郁鍵 螳ロ 覈襦 open 誤一企 蠏 碁 printf 狩 fprintf 伎 豢ル 蟆郁骸 abc.txt 蠍磯. FILE* fp = fopen( abc.txt, w ) ; fprintf( fp, %d %dn, 1, 2 );
15 Formatted I/O Function fprintf() 則 fscanf() 豌襴襯 scanf()覓語企. 豌 語 fopen 伎 所鍵 螳ロ 覈襦 open 誤一企 蠏 碁 scanf 狩 abc.txt 伎 scanf 伎 襦蠏碁 企 曙企れ讌 int i, j ; FILE* fp = fopen( abc.txt, r ) ; fscanf( fp, %d %d, &i, &j );
16 feof() Function 則 feof() file pointer螳 file 蟾讌 曙讌襯 覲企 int feof( FILE *stream ); open file pointer name Returns none-zero : EOF 蟆曙 0 : EOF螳 蟆曙
17 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { int i, j, k ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("cal.txt", "w" ) ; fscanf( ifp, "%d %d %d", &i, &j, &k ) ; fprintf( ofp, "sum: %dn", i + j + k ) ; fclose( ifp ) ; fclose( ofp ) ; return 0 ; } 則 fprintf(), fscanf() 1 2 3 abc.txt cal.txt
18 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { int i, j, k ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("cal.txt", "w" ) ; fscanf( ifp, "%d %d %d", &i, &j, &k ) ; fprintf( ofp, "sum: %dn", i + j + k ) ; fclose( ifp ) ; fclose( ofp ) ; return 0 ; } 則 fprintf(), fscanf() 1 2 3 abc.txt This is a file. cal.txt
19 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { int i, j, k ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("cal.txt", "a" ) ; fscanf( ifp, "%d %d %d", &i, &j, &k ) ; fprintf( ofp, "sum: %dn", i + j + k ) ; fclose( ifp ) ; fclose( ofp ) ; return 0; } 則 fprintf(), fscanf() 1 2 3 abc.txt This is a file. cal.txt
20 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { char c ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("abc2.txt", "a" ) ; while( feof(ifp) == 0 ) { fscanf( ifp, "%c", &c ) ; fprintf( ofp, "%c", c ) ; } fclose( ifp ) ; fclose( ofp ) ; return 0; } 則 fprintf(), fscanf() This is a file. 1 2 3 abc.txt
21 蠍壱 豢 則 fgetc() , getc() file襦 覿 覓語襯 暑 . 襷 伎 曙 覓語螳 朱 EOF襯 覦 fgetc getc 狩. char c ; FILE *fp = fopen("abc.txt", "r" ) ; while( (c = fgetc(fp)) != EOF ) printf("%c", c ) ; int fgetc ( FILE *stream ) ;
22 蠍壱 豢 則 fputc() , putc() File 覓語襯 磯 . fputc putc 狩. char c ; FILE *fp = fopen("abc.txt", "r" ) ; FILE *ofp = fopen("xyz.txt", "w" ) ; while( (c = fgetc(fp)) != EOF ) fputc( c, ofp ) ; int fputc ( int c, FILE *stream ) ;
23 蠍壱 豢 則 fputs() : Writing a string 殊 puts企. NULL 覿覿 蟾讌 朱 覲旧. 語 炎概覃 螳 螳 襴危. 語 ろ覃 EOF襯 襴危. int fputs(char *str, FILE *fp);
24 蠍壱 豢 FILE *fp; int i; char *data[3]={"to ben","or notn","to ben"}; fp = fopen("abc.txt", "w"); for(i = 0; i<3; i++) fputs(data[i],fp); fclose( fp );
25 蠍壱 豢 則 fgets() : Reading a String 殊 gets fp螳 讌 殊 豕 num 1螳 覓語襯 曙 str 誤誤 覦一伎 ロ. n企 EOF襯 襷覃 所鍵襯 譴螻 NULL ロ. 所鍵螳 炎概覃 str 襴危螻 蠏碁讌 朱 NULL 襴 . char *fgets(char *str, int num, FILE *fp);
26 蠍壱 豢 則 fgets() char s[5] ; FILE* fp = fopen("abc.txt", "r" ) ; fgets( s, 5, fp ) ; 123 1 2 1234567
27 蠍壱 豢 則 gets fgets 谿 gets : n螳 り鍵蟾讌 曙. 蠏碁 n fgets : n螳 り鍵蟾讌 曙. n
28 Accessing a File Randomly 則 殊 覯 所 れ 所 苦朱? char c ; FILE *fp = fopen("abc.txt", "r" ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } abcd efghi abc.txt
29 Accessing a File Randomly 則 rewind() 誤磯ゼ 襷 豌朱 蠍企. void rewind( FILE* ) ; char c ; FILE *fp = fopen("abc.txt", r ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } rewind( fp ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } abcd efghi abc.txt
30 Accessing a File Randomly 則 fseek() place offset襷 伎 豺 file position indicator襯 . place 螳 0 (殊 襷豌 ), 1 (豺), 2(襷) 螳 螳. fseek( file_ptr, offset, place);
31 Accessing a File Randomly 則 fseek() fseek( file_ptr, offset, place); 0 (殊 襷豌 ) 1 (豺) 2(襷) 0123456789 abcdefghjk abc.txt
32 Accessing a File Randomly 則 ftell() file position indicator 螳 return. return 螳 豌 0朱 螻 豌覿 覈 byte 伎 螳 螳 碁. 朱覿 覓語 曙 襷 indicator 螳 1讀螳 . int ftell( FILE* );
33 Accessing a File Randomly 則 ftell() char c ; int pos ; FILE *fp = fopen("abc.txt", r ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%d: %cn", ftell(fp), c ) ; } abcd efghi abc.txt
34 stdin, stdout & stderr 則 fprintf襯 伎 覃伎 豢ロ蠍 stdout 覃伎 覩誤 誤一. 則 fscanf襯 伎 る慨 所鍵 stdin る慨襯 覩誤 誤一. printf( This is a testn ) ; fprintf( stdout, This is a testn ) ; scanf( %d, &k ) ; fscanf( stdin, %d, &k ) ;
35 stdin, stdout & stderr Standard C files in stdio.h Written in C Name Remark stdin standard input file connected to the keyboard stdout standard output file connected to the screen stderr standard error file connected to the screen 則 stdio.h 3螳讌 file pointer
36 stdin, stdout & stderr #include <stdio.h> int main() { int k, j ; fscanf( stdin, "%d %d", &k, &j ) ; fprintf( stdout, "Sum: %dn", k + j ) ; fprintf( stderr, "OKn") ; return 0 ; }

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14. fiile io

  • 2. 2 File 豢 則 讌蠍蟾讌 襦蠏碁 豢 : Keyboard 豢: Monitor 則 襭襯 殊 曙伎 豢レ 朱 蟾? 蟲 1 80 90 70 2 80 60 40 3 60 50 70 C program 蟲 蠏 1 80 90 70 80 2 80 60 40 60 3 60 50 70 60
  • 3. 3 File 豢 則 殊 伎 豢 谿 企 願鍵 殊 所鍵 殊 郁鍵 蠍 fopen fscanf, fprintf, fgets, fputs, fclose
  • 4. 4 File Operation Function fopen() 則 fopen() 碁 file 襦蠏碁 蠍 譴觜る 覈 レ 伎 覈 殊 fopen 牛 譴觜伎 Return螳: FILE 蟲譟一牡 pointer 殊 所鍵 轟 郁鍵 fopen 覦 FILE pointer襯 牛伎 企伎 則 fopen() Syntax FILE *fopen( const char *filename, const char *mode ); file pointer襦 return disk filename file open mode
  • 5. 5 File Operation Function fopen() 則 fopen() 殊 襭襯 所鍵 伎 殊 譴觜 my_file.txt 所鍵覈襦 譴觜 襷 殊 朱 NULL 覦 FILE *fp ; fp = fopen(my_file.txt, r);
  • 6. 6 File Operation Function fopen() 則 fopen() 殊 襭襯 郁鍵 伎 殊 譴觜 my_file.txt襯 郁鍵覈襦 譴觜 襷 殊 朱 my_file.txt 焔 襷 企 my_file.txt螳 譟伎覃, 蠏 覈 伎 讌讌 FILE *fp ; fp = fopen(my_file.txt, w);
  • 7. 7 File Operation Function fopen() 則 fopen() 殊 襭襯 豢螳襦 郁鍵 伎 殊 譴觜 my_file.txt襯 append覈襦 譴觜 襷 殊 朱 my_file.txt 焔 襷 企 my_file.txt螳 譟伎覃, 蠍一ヾ 伎 蠏碁襦 讌螻 襦 一讌 蟆 襷讌襷 豢螳 FILE *fp ; fp = fopen(my_file.txt, a);
  • 8. 8 File Operation Function fopen() 則 fopen() 殊 襭襯 所 郁鍵襯 伎 殊 譴觜 my_file.txt 所鍵 郁鍵螳 覈 螳ロ 覈襦 譴觜 襷 my_file.txt 朱 NULL 覦 襷 my_file.txt 朱 open螻, my_file.txt 伎 覈 讌 所鍵 郁鍵 殊 襷 豌 豺 FILE *fp ; fp = fopen(my_file.txt, r+);
  • 9. 9 File Operation Function fopen() 則 fopen() 殊 襭襯 所 郁鍵襯 伎 殊 譴觜 my_file.txt 所鍵 郁鍵螳 覈 螳ロ 覈襦 譴觜 襷 my_file.txt 朱 my_file.txt螳 焔 襷 my_file.txt 朱 open覃伎, my_file.txt 伎 覈 讌讌 FILE *fp ; fp = fopen(my_file.txt, w+);
  • 10. 10 File Operation Function fopen() 則 fopen() 殊 襭襯 所 郁鍵襯 伎 殊 譴觜 my_file.txt 所鍵 郁鍵螳 覈 螳ロ 覈襦 譴觜 襷 my_file.txt 朱 my_file.txt螳 焔 襷 my_file.txt 朱 open螻, my_file.txt 伎 覈 讌 所鍵 郁鍵 殊 襷 襷讌襷 FILE *fp ; fp = fopen(my_file.txt, a+);
  • 11. 11 File pointer 則 File pointer File I/O disk file覈 file pointer襯 牛 stream 燕 . 則 FILE Type stdio.h file typedef襦 type朱 file 覲企ゼ 襦 struct type [Ex] FILE *fp; /* file pointer襦 fp */
  • 12. 12 File Operation Function fclose() 則 fclose() fopen朱 open 殊 覃 fclose襯 覦 殊 . 則 fclose() Syntax int fclose( FILE *stream ); open file pointer name Returns 0 : successful EOF : error (EOF is defined as 1 in stdio.h)
  • 13. 13 File Operation Function fopen() 則 fclose() #include <stdio.h> int main() { FILE *fp ; fp = fopen(my_file.txt, r); ... fclose( fp ) ; return 0 }
  • 14. 14 Formatted I/O Function fprintf() 則 fprintf() 豌襴襯 printf()覓語企. 豌 語 fopen 伎 郁鍵 螳ロ 覈襦 open 誤一企 蠏 碁 printf 狩 fprintf 伎 豢ル 蟆郁骸 abc.txt 蠍磯. FILE* fp = fopen( abc.txt, w ) ; fprintf( fp, %d %dn, 1, 2 );
  • 15. 15 Formatted I/O Function fprintf() 則 fscanf() 豌襴襯 scanf()覓語企. 豌 語 fopen 伎 所鍵 螳ロ 覈襦 open 誤一企 蠏 碁 scanf 狩 abc.txt 伎 scanf 伎 襦蠏碁 企 曙企れ讌 int i, j ; FILE* fp = fopen( abc.txt, r ) ; fscanf( fp, %d %d, &i, &j );
  • 16. 16 feof() Function 則 feof() file pointer螳 file 蟾讌 曙讌襯 覲企 int feof( FILE *stream ); open file pointer name Returns none-zero : EOF 蟆曙 0 : EOF螳 蟆曙
  • 17. 17 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { int i, j, k ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("cal.txt", "w" ) ; fscanf( ifp, "%d %d %d", &i, &j, &k ) ; fprintf( ofp, "sum: %dn", i + j + k ) ; fclose( ifp ) ; fclose( ofp ) ; return 0 ; } 則 fprintf(), fscanf() 1 2 3 abc.txt cal.txt
  • 18. 18 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { int i, j, k ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("cal.txt", "w" ) ; fscanf( ifp, "%d %d %d", &i, &j, &k ) ; fprintf( ofp, "sum: %dn", i + j + k ) ; fclose( ifp ) ; fclose( ofp ) ; return 0 ; } 則 fprintf(), fscanf() 1 2 3 abc.txt This is a file. cal.txt
  • 19. 19 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { int i, j, k ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("cal.txt", "a" ) ; fscanf( ifp, "%d %d %d", &i, &j, &k ) ; fprintf( ofp, "sum: %dn", i + j + k ) ; fclose( ifp ) ; fclose( ofp ) ; return 0; } 則 fprintf(), fscanf() 1 2 3 abc.txt This is a file. cal.txt
  • 20. 20 Formatted I/O Function fprintf() and fscanf() #include <stdio.h> int main() { char c ; FILE *ifp, *ofp ; ifp = fopen("abc.txt", "r" ) ; ofp = fopen("abc2.txt", "a" ) ; while( feof(ifp) == 0 ) { fscanf( ifp, "%c", &c ) ; fprintf( ofp, "%c", c ) ; } fclose( ifp ) ; fclose( ofp ) ; return 0; } 則 fprintf(), fscanf() This is a file. 1 2 3 abc.txt
  • 21. 21 蠍壱 豢 則 fgetc() , getc() file襦 覿 覓語襯 暑 . 襷 伎 曙 覓語螳 朱 EOF襯 覦 fgetc getc 狩. char c ; FILE *fp = fopen("abc.txt", "r" ) ; while( (c = fgetc(fp)) != EOF ) printf("%c", c ) ; int fgetc ( FILE *stream ) ;
  • 22. 22 蠍壱 豢 則 fputc() , putc() File 覓語襯 磯 . fputc putc 狩. char c ; FILE *fp = fopen("abc.txt", "r" ) ; FILE *ofp = fopen("xyz.txt", "w" ) ; while( (c = fgetc(fp)) != EOF ) fputc( c, ofp ) ; int fputc ( int c, FILE *stream ) ;
  • 23. 23 蠍壱 豢 則 fputs() : Writing a string 殊 puts企. NULL 覿覿 蟾讌 朱 覲旧. 語 炎概覃 螳 螳 襴危. 語 ろ覃 EOF襯 襴危. int fputs(char *str, FILE *fp);
  • 24. 24 蠍壱 豢 FILE *fp; int i; char *data[3]={"to ben","or notn","to ben"}; fp = fopen("abc.txt", "w"); for(i = 0; i<3; i++) fputs(data[i],fp); fclose( fp );
  • 25. 25 蠍壱 豢 則 fgets() : Reading a String 殊 gets fp螳 讌 殊 豕 num 1螳 覓語襯 曙 str 誤誤 覦一伎 ロ. n企 EOF襯 襷覃 所鍵襯 譴螻 NULL ロ. 所鍵螳 炎概覃 str 襴危螻 蠏碁讌 朱 NULL 襴 . char *fgets(char *str, int num, FILE *fp);
  • 26. 26 蠍壱 豢 則 fgets() char s[5] ; FILE* fp = fopen("abc.txt", "r" ) ; fgets( s, 5, fp ) ; 123 1 2 1234567
  • 27. 27 蠍壱 豢 則 gets fgets 谿 gets : n螳 り鍵蟾讌 曙. 蠏碁 n fgets : n螳 り鍵蟾讌 曙. n
  • 28. 28 Accessing a File Randomly 則 殊 覯 所 れ 所 苦朱? char c ; FILE *fp = fopen("abc.txt", "r" ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } abcd efghi abc.txt
  • 29. 29 Accessing a File Randomly 則 rewind() 誤磯ゼ 襷 豌朱 蠍企. void rewind( FILE* ) ; char c ; FILE *fp = fopen("abc.txt", r ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } rewind( fp ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%c", c ) ; } abcd efghi abc.txt
  • 30. 30 Accessing a File Randomly 則 fseek() place offset襷 伎 豺 file position indicator襯 . place 螳 0 (殊 襷豌 ), 1 (豺), 2(襷) 螳 螳. fseek( file_ptr, offset, place);
  • 31. 31 Accessing a File Randomly 則 fseek() fseek( file_ptr, offset, place); 0 (殊 襷豌 ) 1 (豺) 2(襷) 0123456789 abcdefghjk abc.txt
  • 32. 32 Accessing a File Randomly 則 ftell() file position indicator 螳 return. return 螳 豌 0朱 螻 豌覿 覈 byte 伎 螳 螳 碁. 朱覿 覓語 曙 襷 indicator 螳 1讀螳 . int ftell( FILE* );
  • 33. 33 Accessing a File Randomly 則 ftell() char c ; int pos ; FILE *fp = fopen("abc.txt", r ) ; while( !foef(fp) ) { fscanf( fp, "%c", &c ) ; printf("%d: %cn", ftell(fp), c ) ; } abcd efghi abc.txt
  • 34. 34 stdin, stdout & stderr 則 fprintf襯 伎 覃伎 豢ロ蠍 stdout 覃伎 覩誤 誤一. 則 fscanf襯 伎 る慨 所鍵 stdin る慨襯 覩誤 誤一. printf( This is a testn ) ; fprintf( stdout, This is a testn ) ; scanf( %d, &k ) ; fscanf( stdin, %d, &k ) ;
  • 35. 35 stdin, stdout & stderr Standard C files in stdio.h Written in C Name Remark stdin standard input file connected to the keyboard stdout standard output file connected to the screen stderr standard error file connected to the screen 則 stdio.h 3螳讌 file pointer
  • 36. 36 stdin, stdout & stderr #include <stdio.h> int main() { int k, j ; fscanf( stdin, "%d %d", &k, &j ) ; fprintf( stdout, "Sum: %dn", k + j ) ; fprintf( stderr, "OKn") ; return 0 ; }