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comparison docs/ccguide/getc.refentry @ 597:2e76fecc5ca0
All refentries finished.
| author | roug |
|---|---|
| date | Fri, 15 Nov 2002 21:49:51 +0000 |
| parents | 253b6096ee01 |
| children | 94ff9d15614f |
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| 596:fe8e46eca1ed | 597:2e76fecc5ca0 |
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| 28 | 28 |
| 29 </refsynopsisdiv> | 29 </refsynopsisdiv> |
| 30 | 30 |
| 31 <refsect1><title>Description</title> | 31 <refsect1><title>Description</title> |
| 32 <para> | 32 <para> |
| 33 Placeholder | 33 Getc returns the next character from the file pointed to by |
| 34 "fp". | |
| 35 </para> | |
| 36 <para> | |
| 37 Getchar is equivalent to "getc(stdin)". | |
| 38 </para> | |
| 39 <para> | |
| 40 Getw returns the next two bytes from the file as an integer. | |
| 41 </para> | |
| 42 <para> | |
| 43 Under OS-9 there is a choice of service requests to use when | |
| 44 reading from a file. "Read()" will get characters up to a | |
| 45 specified number in "raw" mode i.e. no editing will take | |
| 46 place on the input stream and the characters will appear to the | |
| 47 program exactly as in the file. "Readln()", on the other | |
| 48 hand, will honor the various mappings of characters | |
| 49 associated with a Serial Character device such as a terminal | |
| 50 and in any case will return to the caller as soon as a carriage | |
| 51 return is seen on the input. | |
| 52 </para> | |
| 53 <para> | |
| 54 In the vast majority of cases, it is preferable to use | |
| 55 "readln()" for accessing Serial Character devices and "read()" | |
| 56 for any other file input. "Getc()" uses this strategy and, as | |
| 57 all file input using the Standard Library functions is routed | |
| 58 through "getc()", so do all the other input functions. The | |
| 59 choice is made when the first call to "getc()" is made after | |
| 60 the file has been opened. The system is consulted for the | |
| 61 status of the file and a flag bit is set in the file structure | |
| 62 accordingly. The choice may be forced by the programmer by | |
| 63 setting the relevant bit before a call to "getc()". The flag | |
| 64 bits are defined in "<stdio.h>" and "_SCF" and "_RBF" and the | |
| 65 method is as follows: assuming that the file pointer for the | |
| 66 file, as returned by "fopen()" is f, | |
| 67 <programlisting> | |
| 68 f->_flag |= _SCF; | |
| 69 </programlisting> | |
| 70 will force the use of "readln()" on input and | |
| 71 <programlisting> | |
| 72 f->_flag |= _RBF; | |
| 73 </programlisting> | |
| 74 will force the use of "read()". This trick may be played on | |
| 75 the standard streams "stdin", "stdout" and "stderr" without the | |
| 76 need for calling "fopen()" but before any input is requested | |
| 77 from the stream. | |
| 34 </para> | 78 </para> |
| 35 </refsect1> | 79 </refsect1> |
| 36 | 80 |
| 37 <refsect1><title>Diagnostics</title> | 81 <refsect1><title>Diagnostics</title> |
| 38 <para> | 82 <para> |