c - 通过指针修改 const 限定对象

Question

以下代码按我的预期编译和运行。

#include <stdio.h>

int main(void) {
      const char        C1 = '1';
      char const        C2 = '3';

      printf("%c %c", C1, C2);

      char *pC1 = &C1; *pC1 = 'H';
      char *pC2 = &C2; *pC2 = 'o';

      printf("%c %c", C1, C2);

      return 0;
}

这段代码调用了未定义的行为？

Answer 1

是的，这段代码调用了未定义的行为。根据C标准，

If an attempt is made to modify an object defined with a const-qualified type through use of an lvalue with non-const-qualified type, the behavior is undefined.