Question

我写了一个小的c程序来打印对应于值129的扩展ASCII字符

#include<stdio.h>
int main(void)
{
  char a = 129;
  printf("%c\n",a);
  return(0);
}

在bash终端上的unix机器（fedora 16）上编译并运行它。它给出了错误的显示。它在背面显示一个带有白色椭圆形背景的问号。

事实上，如果我把一个= = 126以上的东西，它显示的是同一个问号。

为什么如此以及如何纠正它？

Answer 1

首先，我怀疑这是bash的错; bash只是找到你的程序并运行它，而实际显示程序的输出是你的终端应用程序的工作。其次，127以上没有ASCII字符。尝试打印128..255范围内的字符将发出一个具有给定值的字节，但该字节的显示方式由终端及其配置方式决定。最有可能的是，您的终端期望所有程序输出都以UTF-8编码;为了向后兼容ASCII，所有小于128的字节都是UTF-8中的有效字符，但是当涉及字节128及以上时，只有某些序列有效，并且设置了高位的单个字节是错误的。尝试从单个程序按顺序打印字节226,152和131;如果你看到一个雪人，你会知道你的终端正在使用UTF-8。

Answer 2

为什么你认为ascii字符高于127？

http://en.wikipedia.org/wiki/ASCII

ascii基本上是7位，0-127

Answer 3

我写了一个bash脚本来显示ascii 0-127 + extended 128-255。它取决于系统代码页，终端/控制台等。

Chars 0 - 31,127显示非printables表的代码。所有其他都是印在屏幕上的原始字符。



#!/bin/sh
#
# asciie
#
# print the extended ascii table per the codepage of the current computer
#

# cls
echo -e \\033c

# headings for each column
echo -n "DEC HEX CHR"
printf " | DEC HEX CHR%.0s" {1..7}
printf "\n"

# div
echo -n "- - - - - - "
printf "| - - - - - - %.0s" {1..7}
printf "\n"


# begin character table for ascii 0 to 127 characters
tb=( 'NUL' 'SOH' 'STX' 'ETX' 'EOT' 'ENQ' 'ACK' 'BEL' 'BS ' 'HT ' 'LF ' 'VT ' 'FF ' 'CR ' 'SO ' 'SI ' \
'DLE' 'DC1' 'DC2' 'DC3' 'DC4' 'NAK' 'SYN' 'ETB' 'CAN' 'EM ' 'SUB' 'ESC' 'FS ' 'GS ' 'RS ' 'US ' \
'   ' '!  ' '"  ' '#  ' '$  ' '%  ' '&  '  \'   '(  ' ')  ' '   ' '+  ' ',  ' '-  ' '.  ' '/  ' \
'0  ' '1  ' '2  ' '3  ' '4  ' '5  ' '6  ' '7  ' '8  ' '9  ' ':  ' ';  ' '<  ' '=  ' '>  ' '?  ' \
'@  ' 'A  ' 'B  ' 'C  ' 'D  ' 'E  ' 'F  ' 'G  ' 'H  ' 'I  ' 'J  ' 'K  ' 'L  ' 'M  ' 'N  ' 'O  ' \
'P  ' 'Q  ' 'R  ' 'S  ' 'T  ' 'U  ' 'V  ' 'W  ' 'X  ' 'Y  ' 'Z  ' '[  ' '\  ' ']  ' '^  ' '_  ' \
'`  ' 'a  ' 'b  ' 'c  ' 'd  ' 'e  ' 'f  ' 'g  ' 'h  ' 'i  ' 'j  ' 'k  ' 'l  ' 'm  ' 'n  ' 'o  ' \
'p  ' 'q  ' 'r  ' 's  ' 't  ' 'u  ' 'v  ' 'w  ' 'x  ' 'y  ' 'z  ' '{  ' '|  ' '}  ' '~  ' 'DEL' \
)
# end of character table


# display the regular ascii characters 0 to 127
for a in `seq 0 15`
do

  let "b=$a+16"; let "c=b+16"; let "d=c+16"; let "e=d+16"; let "f=e+16"; let "g=f+16"; let "h=g+16"


  printf "%03d %03X % 3s | %03d %03X % 3s | " $a $a ${tb[$a]} $b $b ${tb[$b]}
  printf "%03d %03X \\$(printf %03o $c)   | %03d %03X \\$(printf %03o $d)   | " $c $c $d $d
  printf "%03d %03X \\$(printf %03o $e)   | %03d %03X \\$(printf %03o $f)   | " $e $e $f $f
  printf "%03d %03X \\$(printf %03o $g)   | " $g $g

  if [[ $a -lt 15 ]];then
    printf "%03d %03X \\$(printf %03o $h) \n" $h $h

  else
    printf "%03d %03X %03s \n" $h $h ${tb[$h]}

  fi

done
# end reg ascii

# begin extended ascii section
echo ' '

# display the extended ascii characters 128 to 255
for a in `seq 128 143`
do

  let "b=$a+16"; let "c=b+16"; let "d=c+16"; let "e=d+16"; let "f=e+16"; let "g=f+16"; let "h=g+16"

  printf "%03d %03X \\$(printf %03o $a)   | %03d %03X \\$(printf %03o $b)   | " $a $a $b $b
  printf "%03d %03X \\$(printf %03o $c)   | %03d %03X \\$(printf %03o $d)   | " $c $c $d $d
  printf "%03d %03X \\$(printf %03o $e)   | %03d %03X \\$(printf %03o $f)   | " $e $e $f $f
  printf "%03d %03X \\$(printf %03o $g)   | %03d %03X \\$(printf %03o $h) \n" $g $g $h $h

done

# div
echo -n "- - - - - - "
printf "| - - - - - - %.0s" {1..7}
printf "\n"

 # display footers for each column
echo -n "DEC HEX CHR"
printf " | DEC HEX CHR%.0s" {1..7}
printf "\n"

# EOF #

#!/bin/sh # # asciie # # print the extended ascii table per the codepage of the current computer # # cls echo -e \\033c # headings for each column echo -n "DEC HEX CHR" printf " | DEC HEX CHR%.0s" {1..7} printf "\n" # div echo -n "- - - - - - " printf "| - - - - - - %.0s" {1..7} printf "\n" # begin character table for ascii 0 to 127 characters tb=( 'NUL' 'SOH' 'STX' 'ETX' 'EOT' 'ENQ' 'ACK' 'BEL' 'BS ' 'HT ' 'LF ' 'VT ' 'FF ' 'CR ' 'SO ' 'SI ' \ 'DLE' 'DC1' 'DC2' 'DC3' 'DC4' 'NAK' 'SYN' 'ETB' 'CAN' 'EM ' 'SUB' 'ESC' 'FS ' 'GS ' 'RS ' 'US ' \ ' ' '! ' '" ' '# ' '$ ' '% ' '& ' \' '( ' ') ' ' ' '+ ' ', ' '- ' '. ' '/ ' \ '0 ' '1 ' '2 ' '3 ' '4 ' '5 ' '6 ' '7 ' '8 ' '9 ' ': ' '; ' '< ' '= ' '> ' '? ' \ '@ ' 'A ' 'B ' 'C ' 'D ' 'E ' 'F ' 'G ' 'H ' 'I ' 'J ' 'K ' 'L ' 'M ' 'N ' 'O ' \ 'P ' 'Q ' 'R ' 'S ' 'T ' 'U ' 'V ' 'W ' 'X ' 'Y ' 'Z ' '[ ' '\ ' '] ' '^ ' '_ ' \ '` ' 'a ' 'b ' 'c ' 'd ' 'e ' 'f ' 'g ' 'h ' 'i ' 'j ' 'k ' 'l ' 'm ' 'n ' 'o ' \ 'p ' 'q ' 'r ' 's ' 't ' 'u ' 'v ' 'w ' 'x ' 'y ' 'z ' '{ ' '| ' '} ' '~ ' 'DEL' \ ) # end of character table # display the regular ascii characters 0 to 127 for a in `seq 0 15` do let "b=$a+16"; let "c=b+16"; let "d=c+16"; let "e=d+16"; let "f=e+16"; let "g=f+16"; let "h=g+16" printf "%03d %03X % 3s | %03d %03X % 3s | " $a $a ${tb[$a]} $b $b ${tb[$b]} printf "%03d %03X \\$(printf %03o $c) | %03d %03X \\$(printf %03o $d) | " $c $c $d $d printf "%03d %03X \\$(printf %03o $e) | %03d %03X \\$(printf %03o $f) | " $e $e $f $f printf "%03d %03X \\$(printf %03o $g) | " $g $g if [[ $a -lt 15 ]];then printf "%03d %03X \\$(printf %03o $h) \n" $h $h else printf "%03d %03X %03s \n" $h $h ${tb[$h]} fi done # end reg ascii # begin extended ascii section echo ' ' # display the extended ascii characters 128 to 255 for a in `seq 128 143` do let "b=$a+16"; let "c=b+16"; let "d=c+16"; let "e=d+16"; let "f=e+16"; let "g=f+16"; let "h=g+16" printf "%03d %03X \\$(printf %03o $a) | %03d %03X \\$(printf %03o $b) | " $a $a $b $b printf "%03d %03X \\$(printf %03o $c) | %03d %03X \\$(printf %03o $d) | " $c $c $d $d printf "%03d %03X \\$(printf %03o $e) | %03d %03X \\$(printf %03o $f) | " $e $e $f $f printf "%03d %03X \\$(printf %03o $g) | %03d %03X \\$(printf %03o $h) \n" $g $g $h $h done # div echo -n "- - - - - - " printf "| - - - - - - %.0s" {1..7} printf "\n" # display footers for each column echo -n "DEC HEX CHR" printf " | DEC HEX CHR%.0s" {1..7} printf "\n" # EOF #

bash不显示126以上的扩展ASCII字符

3 个答案: