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83 lines
3.0 KiB
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83 lines
3.0 KiB
Plaintext
Content-Type: text/x-zim-wiki
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Wiki-Format: zim 0.4
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Creation-Date: 2012-12-25T21:45:29+08:00
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====== gdb pointer ======
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Created Tuesday 25 December 2012
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[geekard@geekard elf]$ **cat array.c**
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#include <stdio.h>
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#include <stdlib.h>
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int main(void)
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{
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int ia[3] = {1,2,3};
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char *cpa[3] = {"Tom", "John", NULL};
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char *cpa2[] = {"Tom", "John", NULL};
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char **cpa3 = {"Tom", "John", NULL};
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}
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[geekard@geekard elf]$ **gcc -g array.c -o array**
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array.c: In function ‘main’:
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array.c:9:4: warning: initialization from incompatible pointer type [enabled by default]
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array.c:9:4: warning: (near initialization for ‘cpa3’) [enabled by default]
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array.c:9:4: warning: excess elements in scalar initializer [enabled by default]
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array.c:9:4: warning: (near initialization for ‘cpa3’) [enabled by default]
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array.c:9:4: warning: excess elements in scalar initializer [enabled by default]
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array.c:9:4: warning: (near initialization for ‘cpa3’) [enabled by default]
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[geekard@geekard elf]$ **gdb array**
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GNU gdb (GDB) 7.5.1
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。。。。。
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**(gdb) list main**
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1 #include <stdio.h>
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2 #include <stdlib.h>
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3
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4 int main(void)
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5 {
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6 int ia[3] = {1,2,3};
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7 char *cpa[3] = {"Tom", "John", NULL};
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8 char *cpa2[] = {"Tom", "John", NULL}; //ia, cpa, cpa2为数组首地址的引用名称，而非变量，不占用
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9 char **cpa3 = {"Tom", "John", NULL};
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10 }
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**(gdb) b 10**
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Breakpoint 1 at 0x8048418: file array.c, line 10.
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**(gdb) r**
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Starting program: /home/geekard/Code/elf/array
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warning: Could not load shared library symbols for linux-gate.so.1.
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Do you need "set solib-search-path" or "set sysroot"?
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Breakpoint 1, main () at array.c:10
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10 }
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**(gdb) disassemble main**
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Dump of assembler code for function main:
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0x080483cc <+0>: push %ebp
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0x080483cd <+1>: mov %esp,%ebp
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0x080483cf <+3>: sub $0x30,%esp
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0x080483d2 <+6>: movl $0x1,-0x10(%ebp)
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0x080483d9 <+13>: movl $0x2,-0xc(%ebp)
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0x080483e0 <+20>: movl $0x3,-0x8(%ebp)
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0x080483e7 <+27>: movl $0x80484b0,-0x1c(%ebp)
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0x080483ee <+34>: movl $0x80484b4,-0x18(%ebp)
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0x080483f5 <+41>: movl $0x0,-0x14(%ebp)
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0x080483fc <+48>: movl $0x80484b0,-0x28(%ebp)
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0x08048403 <+55>: movl $0x80484b4,-0x24(%ebp)
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0x0804840a <+62>: movl $0x0,-0x20(%ebp)
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0x08048411 <+69>: movl $0x80484b0,-0x4(%ebp)
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=> 0x08048418 <+76>: leave
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0x08048419 <+77>: ret
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End of assembler dump.
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**(gdb) bt**
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#0 main () at array.c:10
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**(gdb) info f 0**
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Stack frame at 0xbffff980:
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eip = 0x8048418 in main (array.c:10); saved eip 0xb7e28605
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source language c.
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Arglist at 0xbffff978, args:
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Locals at 0xbffff978, Previous frame's sp is 0xbffff980
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Saved registers:
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ebp at 0xbffff978, eip at 0xbffff97c
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**(gdb) info locals**
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ia = {1, 2, 3}
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cpa = {0x80484b0 "Tom", 0x80484b4 "John", 0x0}
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cpa2 = {0x80484b0 "Tom", 0x80484b4 "John", 0x0}
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__cpa3 = 0x80484b0__
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//可见ia, cpa, cpa2为数组名称，而cpa3为一指针变量，其值为0x80484b0。
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