$ ldd /usr/local/bin/python3.6

linux-vdso.so.1 => (0x00007fffecbba000)
libpython3.6m.so.1.0 => not found
libpthread.so.0 => /usr/lib64/libpthread.so.0 (0x00007fe1400ff000)
libdl.so.2 => /usr/lib64/libdl.so.2 (0x00007fe13fefb000)
libutil.so.1 => /usr/lib64/libutil.so.1 (0x00007fe13fcf8000)
libm.so.6 => /usr/lib64/libm.so.6 (0x00007fe13f9f6000)
libc.so.6 => /usr/lib64/libc.so.6 (0x00007fe13f628000)
/lib64/ld-linux-x86-64.so.2 (0x00007fe14031b000)

$ find / -name 'libpython3.6m.so.1.0'

/root/Python-3.6.9/libpython3.6m.so.1.0
/usr/local/lib/libpython3.6m.so.1.0

$ vim /etc/ld.so.conf 　　
文件末尾新添加一行，/usr/local/lib/

#include <stdio.h>

struct param {
  int a;
  int b;
  char c;
  float f;
  int arr[3];
  };
  
void print0(struct param arg)
{
  printf("in print:\n");
  printf("a: %d\n", arg.a);
  printf("b: %d\n", arg.b);
  printf("c: %c\n", arg.c);
  printf("f: %f\n", arg.f);
  printf("arr: %d %d %d\n", arg.arr[0], arg.arr[1], arg.arr[2]);
}

void print2(struct param *arg)
{
  printf("in print2 :\n");
  printf("a: %d\n", arg->a);
  printf("b: %d\n", arg->b);
  printf("c: %c\n", arg->c);
  printf("f: %f\n", arg->f);
  printf("arr: %d %d %d\n", arg->arr[0], arg->arr[1], arg->arr[2]);
}

void print3(int a)
{
  printf("in print3:\n");
  printf("a: %d\n", a);
}

from ctypes import *

class ss(Structure):
  _fields_ = [
  ("a", c_int),
  ("b", c_int),
  ("c", c_char),
  ("f", c_float),
  ("arr", c_int*3), //定义数组
  ]

#加载动态库
fileName = "/home/primax/Desktop/Work/Test/python/dll.so"
lib = cdll.LoadLibrary(fileName)
#定义变量
param = ss()
#给结构体赋值
param.a = 1
param.b = 2
param.c = 'a'
param.f = 1.2345
param.arr[0] = 0
param.arr[1] = 1
param.arr[2] = 2

lib.print0(param)
lib.print3(2)
#传指针 pointer取指针
lib.print2(pointer(param))