fig14_06.c

C程序设计经典教程第5版程序示例,比较适合初级c语言的学生

/* Fig. 14.6: fig14_06.c
   Using temporary files */
#include <stdio.h>

int main( void )
{
   FILE *filePtr;     /* pointer to file being modified */
   FILE *tempFilePtr; /* temporary file pointer */
   int c; /* define c to hold characters read from a file */
   char fileName[ 30 ]; /* create char array */

   printf( "This program changes tabs to spaces.\n"
      "Enter a file to be modified: " );
   scanf( "%29s", fileName );

   /* fopen opens the file */
   if ( ( filePtr = fopen( fileName, "r+" ) ) != NULL ) {

      /* create temporary file */
      if ( ( tempFilePtr = tmpfile() ) != NULL ) {
         printf( "\nThe file before modification is:\n" );

         /* read characters from file and place in temporary file */
         while ( ( c = getc( filePtr ) ) != EOF ) {
            putchar( c );
            putc( c == '\t' ? ' ': c, tempFilePtr );
         } /* end while */

         rewind( tempFilePtr ); 
         rewind( filePtr );
         printf( "\n\nThe file after modification is:\n" );

         /* read from temporary file and write into original file */
         while ( ( c = getc( tempFilePtr ) ) != EOF ) {
            putchar( c );
            putc( c, filePtr );
         } /* end while */

      } /* end if */
      else { /* if temporary file could not be opened */
         printf( "Unable to open temporary file\n" );
      } /* end else */

   } /* end if */  
   else { /* if file could not be opened */
      printf( "Unable to open %s\n", fileName );
   } /* end else */

   return 0; /* indicates successful termination */

} /* end main */


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