Red Hat ENTERPRISE LINUX 4 - DEVELOPER TOOLS GUIDE, Руководство пользователя

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86 Chapter 10. Examining Data
We can use the
show charset
command to see what character sets gdb is currently using to interpret
and display characters and strings:
(gdb) show charset
The current host and target character set is ‘ISO-8859-1’.
(gdb)
For the sake of printing this manual, let’s use ascii as our initial character set:
(gdb) set charset ASCII
(gdb) show charset
The current host and target character set is ‘ASCII’.
(gdb)
Let’s assume that ascii is indeed the correct character set for our host system -- in other words, let’s as-
sume that if gdb prints characters using the ascii character set, our terminal will display them properly.
Since our current target character set is also ascii, the contents of
ascii_hello
print legibly:
(gdb) print ascii_hello
$1 = 0x401698 "Hello, world!\n"
(gdb) print ascii_hello[0]
$2 = 72 ’H’
(gdb)
gdb uses the target character set for character and string literals you use in expressions:
(gdb) print ’+’
$3 = 43 ’+’
(gdb)
The ascii character set uses the number 43 to encode the
+
character.
gdb relies on the user to tell it which character set the target program uses. If we print
ibm1047_hello
while our target character set is still ascii, we get jibberish:
(gdb) print ibm1047_hello
$4 = 0x4016a8 "\310\205\223\223\226k@\246\226\231\223\204Z%"
(gdb) print ibm1047_hello[0]
$5 = 200 ’\310’
(gdb)
If we invoke the
set target-charset
followed by [TAB][TAB], gdb tells us the character sets it
supports:
(gdb) set target-charset
ASCII
EBCDIC-US IBM1047 ISO-8859-1
(gdb) set target-charset