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1 |
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2 :mod:`curses.ascii` --- Utilities for ASCII characters |
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3 ====================================================== |
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4 |
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5 .. module:: curses.ascii |
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6 :synopsis: Constants and set-membership functions for ASCII characters. |
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7 .. moduleauthor:: Eric S. Raymond <esr@thyrsus.com> |
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8 .. sectionauthor:: Eric S. Raymond <esr@thyrsus.com> |
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9 |
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10 |
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11 .. versionadded:: 1.6 |
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12 |
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13 The :mod:`curses.ascii` module supplies name constants for ASCII characters and |
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14 functions to test membership in various ASCII character classes. The constants |
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15 supplied are names for control characters as follows: |
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16 |
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17 +--------------+----------------------------------------------+ |
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18 | Name | Meaning | |
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19 +==============+==============================================+ |
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20 | :const:`NUL` | | |
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21 +--------------+----------------------------------------------+ |
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22 | :const:`SOH` | Start of heading, console interrupt | |
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23 +--------------+----------------------------------------------+ |
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24 | :const:`STX` | Start of text | |
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25 +--------------+----------------------------------------------+ |
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26 | :const:`ETX` | End of text | |
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27 +--------------+----------------------------------------------+ |
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28 | :const:`EOT` | End of transmission | |
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29 +--------------+----------------------------------------------+ |
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30 | :const:`ENQ` | Enquiry, goes with :const:`ACK` flow control | |
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31 +--------------+----------------------------------------------+ |
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32 | :const:`ACK` | Acknowledgement | |
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33 +--------------+----------------------------------------------+ |
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34 | :const:`BEL` | Bell | |
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35 +--------------+----------------------------------------------+ |
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36 | :const:`BS` | Backspace | |
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37 +--------------+----------------------------------------------+ |
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38 | :const:`TAB` | Tab | |
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39 +--------------+----------------------------------------------+ |
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40 | :const:`HT` | Alias for :const:`TAB`: "Horizontal tab" | |
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41 +--------------+----------------------------------------------+ |
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42 | :const:`LF` | Line feed | |
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43 +--------------+----------------------------------------------+ |
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44 | :const:`NL` | Alias for :const:`LF`: "New line" | |
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45 +--------------+----------------------------------------------+ |
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46 | :const:`VT` | Vertical tab | |
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47 +--------------+----------------------------------------------+ |
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48 | :const:`FF` | Form feed | |
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49 +--------------+----------------------------------------------+ |
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50 | :const:`CR` | Carriage return | |
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51 +--------------+----------------------------------------------+ |
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52 | :const:`SO` | Shift-out, begin alternate character set | |
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53 +--------------+----------------------------------------------+ |
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54 | :const:`SI` | Shift-in, resume default character set | |
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55 +--------------+----------------------------------------------+ |
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56 | :const:`DLE` | Data-link escape | |
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57 +--------------+----------------------------------------------+ |
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58 | :const:`DC1` | XON, for flow control | |
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59 +--------------+----------------------------------------------+ |
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60 | :const:`DC2` | Device control 2, block-mode flow control | |
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61 +--------------+----------------------------------------------+ |
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62 | :const:`DC3` | XOFF, for flow control | |
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63 +--------------+----------------------------------------------+ |
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64 | :const:`DC4` | Device control 4 | |
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65 +--------------+----------------------------------------------+ |
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66 | :const:`NAK` | Negative acknowledgement | |
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67 +--------------+----------------------------------------------+ |
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68 | :const:`SYN` | Synchronous idle | |
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69 +--------------+----------------------------------------------+ |
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70 | :const:`ETB` | End transmission block | |
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71 +--------------+----------------------------------------------+ |
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72 | :const:`CAN` | Cancel | |
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73 +--------------+----------------------------------------------+ |
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74 | :const:`EM` | End of medium | |
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75 +--------------+----------------------------------------------+ |
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76 | :const:`SUB` | Substitute | |
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77 +--------------+----------------------------------------------+ |
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78 | :const:`ESC` | Escape | |
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79 +--------------+----------------------------------------------+ |
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80 | :const:`FS` | File separator | |
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81 +--------------+----------------------------------------------+ |
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82 | :const:`GS` | Group separator | |
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83 +--------------+----------------------------------------------+ |
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84 | :const:`RS` | Record separator, block-mode terminator | |
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85 +--------------+----------------------------------------------+ |
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86 | :const:`US` | Unit separator | |
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87 +--------------+----------------------------------------------+ |
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88 | :const:`SP` | Space | |
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89 +--------------+----------------------------------------------+ |
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90 | :const:`DEL` | Delete | |
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91 +--------------+----------------------------------------------+ |
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92 |
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93 Note that many of these have little practical significance in modern usage. The |
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94 mnemonics derive from teleprinter conventions that predate digital computers. |
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95 |
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96 The module supplies the following functions, patterned on those in the standard |
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97 C library: |
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98 |
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99 |
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100 .. function:: isalnum(c) |
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101 |
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102 Checks for an ASCII alphanumeric character; it is equivalent to ``isalpha(c) or |
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103 isdigit(c)``. |
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104 |
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105 |
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106 .. function:: isalpha(c) |
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107 |
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108 Checks for an ASCII alphabetic character; it is equivalent to ``isupper(c) or |
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109 islower(c)``. |
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110 |
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111 |
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112 .. function:: isascii(c) |
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113 |
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114 Checks for a character value that fits in the 7-bit ASCII set. |
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115 |
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116 |
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117 .. function:: isblank(c) |
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118 |
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119 Checks for an ASCII whitespace character. |
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120 |
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121 |
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122 .. function:: iscntrl(c) |
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123 |
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124 Checks for an ASCII control character (in the range 0x00 to 0x1f). |
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125 |
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126 |
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127 .. function:: isdigit(c) |
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128 |
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129 Checks for an ASCII decimal digit, ``'0'`` through ``'9'``. This is equivalent |
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130 to ``c in string.digits``. |
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131 |
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132 |
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133 .. function:: isgraph(c) |
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134 |
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135 Checks for ASCII any printable character except space. |
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136 |
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137 |
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138 .. function:: islower(c) |
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139 |
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140 Checks for an ASCII lower-case character. |
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141 |
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142 |
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143 .. function:: isprint(c) |
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144 |
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145 Checks for any ASCII printable character including space. |
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146 |
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147 |
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148 .. function:: ispunct(c) |
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149 |
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150 Checks for any printable ASCII character which is not a space or an alphanumeric |
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151 character. |
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152 |
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153 |
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154 .. function:: isspace(c) |
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155 |
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156 Checks for ASCII white-space characters; space, line feed, carriage return, form |
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157 feed, horizontal tab, vertical tab. |
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158 |
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159 |
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160 .. function:: isupper(c) |
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161 |
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162 Checks for an ASCII uppercase letter. |
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163 |
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164 |
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165 .. function:: isxdigit(c) |
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166 |
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167 Checks for an ASCII hexadecimal digit. This is equivalent to ``c in |
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168 string.hexdigits``. |
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169 |
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170 |
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171 .. function:: isctrl(c) |
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172 |
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173 Checks for an ASCII control character (ordinal values 0 to 31). |
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174 |
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175 |
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176 .. function:: ismeta(c) |
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177 |
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178 Checks for a non-ASCII character (ordinal values 0x80 and above). |
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179 |
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180 These functions accept either integers or strings; when the argument is a |
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181 string, it is first converted using the built-in function :func:`ord`. |
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182 |
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183 Note that all these functions check ordinal bit values derived from the first |
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184 character of the string you pass in; they do not actually know anything about |
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185 the host machine's character encoding. For functions that know about the |
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186 character encoding (and handle internationalization properly) see the |
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187 :mod:`string` module. |
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188 |
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189 The following two functions take either a single-character string or integer |
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190 byte value; they return a value of the same type. |
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191 |
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192 |
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193 .. function:: ascii(c) |
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194 |
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195 Return the ASCII value corresponding to the low 7 bits of *c*. |
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196 |
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197 |
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198 .. function:: ctrl(c) |
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199 |
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200 Return the control character corresponding to the given character (the character |
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201 bit value is bitwise-anded with 0x1f). |
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202 |
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203 |
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204 .. function:: alt(c) |
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205 |
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206 Return the 8-bit character corresponding to the given ASCII character (the |
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207 character bit value is bitwise-ored with 0x80). |
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208 |
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209 The following function takes either a single-character string or integer value; |
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210 it returns a string. |
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211 |
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212 |
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213 .. function:: unctrl(c) |
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214 |
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215 Return a string representation of the ASCII character *c*. If *c* is printable, |
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216 this string is the character itself. If the character is a control character |
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217 (0x00-0x1f) the string consists of a caret (``'^'``) followed by the |
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218 corresponding uppercase letter. If the character is an ASCII delete (0x7f) the |
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219 string is ``'^?'``. If the character has its meta bit (0x80) set, the meta bit |
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220 is stripped, the preceding rules applied, and ``'!'`` prepended to the result. |
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221 |
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222 |
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223 .. data:: controlnames |
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224 |
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225 A 33-element string array that contains the ASCII mnemonics for the thirty-two |
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226 ASCII control characters from 0 (NUL) to 0x1f (US), in order, plus the mnemonic |
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227 ``SP`` for the space character. |
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228 |