您不包括 strtod decl 标头(stdlib.h),因此您使用的是内部 strtod 实现(这似乎只是一个存根?)
root@pinkpony:~# gcc -Wall -g -o t t.c
t.c: In function ‘main’:
t.c:6: warning: implicit declaration of function ‘strtod’
t.c:6: warning: implicit declaration of function ‘getenv’
t.c:8: warning: control reaches end of non-void function
root@pinkpony:~# gdb ./t
Reading symbols from /root/t...done.
(gdb) run
Starting program: /root/t
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7a96b64 in ____strtod_l_internal (nptr=<value optimized out>, endptr=<value optimized out>, group=<value optimized out>, loc=0x7ffff7dd6580) at strtod_l.c:530
5 30 strtod_l.c: No such file or directory.
in strtod_l.c
(gdb) bt
#0 0x00007ffff7a96b64 in ____strtod_l_internal (nptr=<value optimized out>, endptr=<value optimized out>, group=<value optimized out>, loc=0x7ffff7dd6580) at strtod_l.c:530
#1 0x00000000004005bc in main () at t.c:6
(gdb)
忽略 sigsegv,在我的平台上是由 getenv() 引起的,它也在 stdlib 中声明但没有内部 gcc impl