[SOLVED] explanation of char pointer

atlantis43 · 05-23-2013, 04:40 PM

had some experience with 'immediate window' in MSaccessBasic (with a lot of help from access user forums), but that was nice & simple. Never used a true source code debugger before.
With gdb, I know commands like b & d & infolocals, but the real 'programmers' commands like 's' are beyond me, and I can rarely get gdb to show me what's going on in called programs.

PTrenholme · 05-23-2013, 05:09 PM

I don't think anyone mentioned to the OP that escape character precedes the character to be escaped. In many of the posted examples, the backslash seemed to follow the character to be escaped.

atlantis43 · 05-23-2013, 05:21 PM

no----I meant s for 'step' thru code as opposed to n for 'next'

theNbomr · 05-23-2013, 06:17 PM

You don't need to step through code for this.

Code:

? 
? cat literaStringsTest.c 
#include <stdio.h>
#include <stdlib.h>

char  literalString[] = "This literal string has a d-quote \" embedded in it.";

int main( int argc, char * argv[] ){

    puts( "A literal string with a percent-D symbol: %d \n" );
    printf( "A literal string with a percent-D symbol: %%d \n" );
    exit(0);

}
?

Code:

? 
? make CFLAGS+=-g literaStringsTest
cc -g    literaStringsTest.c   -o literaStringsTest
?

Code:

? 
? gdb literaStringsTest
GNU gdb (GDB) 7.0.1-debian
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/bomr/Util/c/literaStringsTest...done.
(gdb) x /56c literalString
0x80496c0 <literalString>:      84 'T'  104 'h' 105 'i' 115 's' 32 ' '  108 'l' 105 'i' 116 't'
0x80496c8 <literalString+8>:    101 'e' 114 'r' 97 'a'  108 'l' 32 ' '  115 's' 116 't' 114 'r'
0x80496d0 <literalString+16>:   105 'i' 110 'n' 103 'g' 32 ' '  104 'h' 97 'a'  115 's' 32 ' '
0x80496d8 <literalString+24>:   97 'a'  32 ' '  100 'd' 45 '-'  113 'q' 117 'u' 111 'o' 116 't'
0x80496e0 <literalString+32>:   101 'e' 32 ' '  34 '"'  32 ' '  101 'e' 109 'm' 98 'b'  101 'e'
0x80496e8 <literalString+40>:   100 'd' 100 'd' 101 'e' 100 'd' 32 ' '  105 'i' 110 'n' 32 ' '
0x80496f0 <literalString+48>:   105 'i' 116 't' 46 '.'  0 '\000'        0 '\000'        0 '\000'        0 '\000'        0 '\000'
(gdb) x /56xb literalString
0x80496c0 <literalString>:      0x54    0x68    0x69    0x73    0x20    0x6c    0x69    0x74
0x80496c8 <literalString+8>:    0x65    0x72    0x61    0x6c    0x20    0x73    0x74    0x72
0x80496d0 <literalString+16>:   0x69    0x6e    0x67    0x20    0x68    0x61    0x73    0x20
0x80496d8 <literalString+24>:   0x61    0x20    0x64    0x2d    0x71    0x75    0x6f    0x74
0x80496e0 <literalString+32>:   0x65    0x20    0x22    0x20    0x65    0x6d    0x62    0x65
0x80496e8 <literalString+40>:   0x64    0x64    0x65    0x64    0x20    0x69    0x6e    0x20
0x80496f0 <literalString+48>:   0x69    0x74    0x2e    0x00    0x00    0x00    0x00    0x00
(gdb)

--- rod.