python调用C库

• 编写C库test.c

  #include <stdio.h>
  #include <string.h>
  int strcmpTest(char *a, char *b)
  {
          return strcmp(a, b);
  }
  void strcpyTest(char *dst, char *src)
  {
          memcpy(dst, src, strlen(dst));
  }
  char *readStr(char *str)
  {
          printf("LibPrint: %s  addr=%p\n", str, str);
          return str;
  }

   将c文件生成动态库：gcc test.c -fPIC -shared -o libtest.so

• 编写python文件调用该库

import ctypes
test = ctypes.CDLL("./libtest.so")
s1 = '0123456789'
s2 = '0123456789'
s3 = '987654321'
print 'strcmp case:'
print test.strcmpTest(s1, s2)
print 'strcpy case:'
test.strcpyTest(s1, s3)
print  s1
print 'readStr case:'
print  test.readStr(s3)

   执行结果如下：

strcmp case:
0
strcpy case:
987654321
readStr case:
LibPrint: 987654321  addr=0x7fb00c1e0fb4
203296692

我用计算器算了一下，203296692 == 0xc1e0fb4(32bits)。我实验的机器是64bits，所以看起来addr要大。并且readStr的返回值到python脚本中，是以32bits有符号存储的。