从文件中读取结构体变量的数据读取和写入结构体数据到文件

#include

size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);

size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);

struct A
{
    int a;
    int b;
    char c;
    double d;
};
void freadtest()
{
    struct A tmp,test;
    tmp.a =1;
    tmp.b= 2;
    tmp.c = 'a';
    tmp.d = 1.235;

    FILE *fd = fopen("a1.txt","a+");
    if(fd == NULL)
        cout<<"open fail"<