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466
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1 <refentry id="getc">
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2 <refnamediv>
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570
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3 <refname>Getc</refname>
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4 <refname>Getchar</refname>
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5 <refname>Getw</refname>
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6 <refpurpose>return next character to be read from a file</refpurpose>
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466
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7 </refnamediv>
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8
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9 <refsynopsisdiv>
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10 <funcsynopsis>
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468
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11 <funcsynopsisinfo>
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12 #include <stdio.h>
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13 </funcsynopsisinfo>
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570
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14
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466
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15 <funcprototype>
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570
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16 <funcdef>int <function>getc</function></funcdef>
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17 <paramdef>FILE *<parameter>fp</parameter></paramdef>
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18 </funcprototype>
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19 <funcprototype>
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20 <funcdef>int <function>getchar</function></funcdef>
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636
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21 <void/>
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570
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22 </funcprototype>
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23 <funcprototype>
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24 <funcdef>int <function>getw</function></funcdef>
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25 <paramdef>FILE *<parameter>fp</parameter></paramdef>
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466
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26 </funcprototype>
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27 </funcsynopsis>
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28
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29 </refsynopsisdiv>
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30
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31 <refsect1><title>Description</title>
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32 <para>
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597
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33 Getc returns the next character from the file pointed to by
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34 "fp".
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35 </para>
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36 <para>
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37 Getchar is equivalent to "getc(stdin)".
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38 </para>
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39 <para>
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40 Getw returns the next two bytes from the file as an integer.
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41 </para>
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42 <para>
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43 Under OS-9 there is a choice of service requests to use when
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44 reading from a file. "Read()" will get characters up to a
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45 specified number in "raw" mode i.e. no editing will take
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46 place on the input stream and the characters will appear to the
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47 program exactly as in the file. "Readln()", on the other
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48 hand, will honor the various mappings of characters
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49 associated with a Serial Character device such as a terminal
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50 and in any case will return to the caller as soon as a carriage
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51 return is seen on the input.
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52 </para>
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53 <para>
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54 In the vast majority of cases, it is preferable to use
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55 "readln()" for accessing Serial Character devices and "read()"
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56 for any other file input. "Getc()" uses this strategy and, as
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57 all file input using the Standard Library functions is routed
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58 through "getc()", so do all the other input functions. The
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59 choice is made when the first call to "getc()" is made after
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60 the file has been opened. The system is consulted for the
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61 status of the file and a flag bit is set in the file structure
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62 accordingly. The choice may be forced by the programmer by
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63 setting the relevant bit before a call to "getc()". The flag
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64 bits are defined in "<stdio.h>" and "_SCF" and "_RBF" and the
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65 method is as follows: assuming that the file pointer for the
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66 file, as returned by "fopen()" is f,
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67 <programlisting>
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68 f->_flag |= _SCF;
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69 </programlisting>
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70 will force the use of "readln()" on input and
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71 <programlisting>
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72 f->_flag |= _RBF;
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73 </programlisting>
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74 will force the use of "read()". This trick may be played on
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75 the standard streams "stdin", "stdout" and "stderr" without the
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76 need for calling "fopen()" but before any input is requested
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77 from the stream.
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466
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78 </para>
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79 </refsect1>
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542
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80
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552
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81 <refsect1><title>Diagnostics</title>
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82 <para>
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83 EOF(-1) is returned for end of file or error.
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84 </para>
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85 </refsect1>
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86
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542
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87 <refsect1><title>See Also</title>
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88 <para>
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89 <link linkend="putc">Putc()</link>,
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90 <link linkend="fread">fread()</link>,
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91 <link linkend="fopen">fopen()</link>,
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92 <link linkend="gets">gets()</link>,
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93 <link linkend="ungetc">ungetc()</link>
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94 </para>
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95 </refsect1>
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96
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466
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97 </refentry>
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