gdb学习5：打印函数堆栈和退出函数

 代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char *MyStrCopy1(const char *s1)
{
  if(NULL == s1)
  {
    return "string is NULL";
  }
  else
  {

    char *s2 = (char *)malloc(strlen(s1)+1);
    if(NULL == s2)
    {
      return "malloc error";
    }
    char *p = s2;
    while((*s2++ = *s1++));
    return p;
  }  
}

char *MyStrCopy2(const char *s1,char *s2)
{
  char *p = s2;
  while(*s2++ == *s1++);
  //while(*s2++ = *s1++);
  return p;
}

int main(int argv,char **argc)
{
  const char *str1 = NULL;
  const char *str2 = "string copying";
  char str3[strlen(str2)+1];
  //char str3[20];
  printf("%s\n",MyStrCopy1(str1));
  printf("%s\n",MyStrCopy1(str2));
  char *res = MyStrCopy2(str2,str3);
  printf("%s\n",res);
  return 0;
}

编译运行：

gyz@debian:~/mc$ gcc strcopy.c -o strcopy -g -Wall
gyz@debian:~/mc$ gdb strcopy

 直接进入新内容。

(gdb) bt
#0  main (argv=1, argc=0x7fffffffe228) at strcopy.c:41
(gdb) s
MyStrCopy2 (s1=0x555555554990 "string copying", s2=0x7fffffffe0c0 "\001")
    at strcopy.c:27
27        char *p = s2;
(gdb) bt
#0  MyStrCopy2 (s1=0x555555554990 "string copying", s2=0x7fffffffe0c0 "\001")
    at strcopy.c:27
#1  0x00005555555548bc in main (argv=1, argc=0x7fffffffe228) at strcopy.c:41
(gdb) finish
Run till exit from #0  MyStrCopy2 (s1=0x555555554990 "string copying", 
    s2=0x7fffffffe0c0 "\001") at strcopy.c:27
0x00005555555548bc in main (argv=1, argc=0x7fffffffe228) at strcopy.c:41
41        char *res = MyStrCopy2(str2,str3);
Value returned is $1 = 0x7fffffffe0c0 "\001"
(gdb) n
42        printf("%s\n",res);
(gdb)

解释：

1，bt（不知道这个是哪个单词的简写，知道的，请留言）可以打印函数堆栈，上面用s进入了函数MyStrCopy2()，可以看到bt打印的信息是层层递进的；

2，finish命令可以直接退出当前函数，不需要再用n一步一步的执行完再退出函数。

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