mktime（）在C中覆盖时间

我对c语言中的

mktime

有问题：

time_t t_fim;
time(&t_fim);

struct tm* p_fim;
struct tm* c_fim;
p_fim = localtime(&t_fim);
c_fim = localtime(&t_fim);

......

p_fim->tm_year = ano-1900;
p_fim->tm_mon = mes-1;
p_fim->tm_mday = dia;
//here the p_fim date is good

c_fim->tm_mday -=47;
mktime(c_fim);

printf("Pascoa %d %d %d\n", p_fim->tm_mday, p_fim->tm_mon + 1, p_fim->tm_year + 1900);
printf("Carnaval %d %d %d\n", c_fim->tm_mday, c_fim->tm_mon+1, c_fim->tm_year + 1900);

//here the c_fim is good with -47 days but the `p_fim` is now equal with `c_fim`

---

mktime

正在更改

p\u fim

的值，如何解决此问题？

尝试删除指针

struct tm p_fim;
struct tm c_fim;
p_fim = *localtime(&t_fim);
c_fim = *localtime(&t_fim);

---

或者，如果您使用的是POSIX系统，请尝试改为

您认为您的

p\u fim

和

c\u fim

变量指向哪里？在您展示的代码中，它们从未初始化或以其他方式设置为指向有效内存。我现在编辑了代码。您应该阅读此文档，尤其是其中的部分：“返回值指向内部对象，其有效性或值可能会因任何后续对gmtime或localtime的调用而改变。”