using gdb to debug c program

#include <stdio.h>
static void display(int i, int *ptr);

int main(void) {
   int x = 5;
   int *xptr = &x;
   printf("In main():\n");
   printf("   x is %d and is stored at %p.\n", x, &x);
   printf("   xptr points to %p which holds %d.\n", xptr, *xptr);
   display(x, xptr);
   return 0;
}

void display(int z, int *zptr) {
   printf("In display():\n");
   printf("   z is %d and is stored at %p.\n", z, &z);
   printf("   zptr points to %p which holds %d.\n", zptr, *zptr);
}

使用上面的file， 比方 test.c

1, 编译。 gcc -g -o testx test.c

2, 执行。 gdb testx

GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1

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Reading symbols from testx...done.

(gdb)

3, 设置断点。 gdb> b 8

Breakpoint 1 at 0x8048472: file test.c, line 8.

4, 设置断点2。 gdb> b 10

Breakpoint 2 at 0x80484ac: file test.c, line 10.

5, 运行。

gdb> run

Starting program: /home/wang/mytest/gdbtest/testx 

In main():





Breakpoint 1, main () at test.c:8

8   printf("   x is %d and is stored at %p.\n", x, &x);

6, 继续。 gdb> c

Continuing.

   x is 5 and is stored at 0xbfffeb58.

   xptr points to 0xbfffeb58 which holds 5.





Breakpoint 2, main () at test.c:10

10   display(x, xptr);

7, 继续。 gdb> c

Continuing.

In display():

   z is 5 and is stored at 0xbfffeb40.

   zptr points to 0xbfffeb58 which holds 5.

[Inferior 1 (process 11616) exited normally]

9, for step, using step

10, for backtrace, using bt