file_processing英文版-資料下載頁
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【正文】 of( struct clientData ), 1, cfPtr )。 printf( Enter account number\n? )。 scanf( %d, )。 } fclose( cfPtr )。 } return 0。 } Writing Data Randomly to a Random Access File ? int fseek( FILE *stream, long int offset, int whence)。 ? Set the file position pointer to a specific position ? stream pointer to file ? offset file position pointer (0 is first location) ? whence specifies where in file we are reading from ? SEEK_SET seek starts at beginning of file ? SEEK_CUR seek starts at current location in file ? SEEK_END seek starts at end of file ? Succeed: return 0 36 Writing Data Randomly to a Random Access File 37 /*Fig. Reading a random access file sequentially */ …… int main() { FILE *cfPtr。 struct clientData client。 if ( ( cfPtr = fopen( , r ) ) == NULL ) printf( File could not be opened.\n )。 else { printf( %6s%16s%11s%10s\n, \ Acct, Last Name, First Name, Balance )。 while ( fread( client, sizeof( struct clientData ), 1, cfPtr ) ) { if ( != 0 ) printf( %6d%16s%11s%\n, \ , , \ , )。 } fclose( cfPtr )。 } return 0。 } Reading Data Sequentially from a Random Access File ? int fread( client, sizeof (struct clientData), 1, myPtr )。 ? Reads a specified number of bytes from a file into memory ? Can read several fixedsize array elements ? Provide pointer to array ? Indicate number of elements to read ? Number specified in the 3rd argument ? return the number of items successfully read 38 Summary 本章重要內(nèi)容： ? C語言中文件的分類 ? 順序文件 (文本文件 )的讀寫操作 ? 隨機文件 (二進制文件 )的讀寫操作 ? 兩類文件的異同 39 A few words on C Preprocessing 40 Introduction ? Handle by the preprocessor ? Not the C plier! ? Processed prior to pilation 編譯前進行 ? All headed with 井號開頭 Procedures to develop a C program 41 define: Symbolic Constants ? Example: define PI ? replacementlist is any sequence of C tokens ? it may include identifiers, keywords, numbers, character constants, string literals, operators, and punctuation. General Form: define identifier replacementlist 42 define: Symbolic Constants General Form: define identifier replacementlist define YES 1 define NO 0 define PI define OUT printf(“Hello,World”)。 define N = 100 define N 100。 define PI 。 43 What will N be replaced by? Symbolic Constants Advantages ? It makes programs easier to read ? It makes programs easier to modify ? It helps avoid inconsistencies and typographical errors 44 演講完畢，謝謝觀看！
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