sizeof

Possible Duplicate: Why isn't sizeof for a struct equal to the sum of sizeof of each member? I was trying to understand the concept of bit fields. But I am not able to find why the size of the following structure in CASE III is coming out as 8 bytes. CASE I: struct B { unsigned char c; // +8 bits } b; sizeof(b); // Output: 1 (because unsigned char takes 1 byte on my system) CASE II: struct B { unsigned b: 1; } b; sizeof(b); // Output: 4 (because unsigned takes 4 bytes on my system) CASE III: struct B { unsigned char c; // +8 bits unsigned b: 1; // +1 bit } b; sizeof(b); // Output: 8 I don't

A CodeForces 1238A Prime Subtraction 水题，除了差1都行。 #include<stdio.h> #include<set> #include<iostream> #define mem(ss) memset(ss,0,sizeof(ss)) #define rep(d, s, t) for(int d=s;d<=t;d++) #define rev(d, s, t) for(int d=s;d>=t;d--) typedef long long ll; typedef long double ld; typedef double db; const ll mod = 998244353; const int N = 1e4 + 10; #define io_opt ios::sync_with_stdio(false);cin.tie(0);cout.tie(0) using namespace std; ll T,x,y; int main(){ scanf("%lld",&T); while(T--){ scanf("%lld%lld",&x,&y); if(x-y==1){ printf("NO\n"); } else{ printf("YES\n"); } } return 0; } B CodeForces 1238B Kill 'Em

介绍 tcp作为服务端，监听端口8888，实现串口透传，这里是使用select监听tcp的receive和串口的read，单工通信 程序 #include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <unistd.h> #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <string.h> #include <errno.h> #include <stdlib.h> #include <linux/serial.h> #include <sys/ioctl.h> #include <sys/select.h> #include <termios.h> void Test_err(int flg) { if(flg<0) { perror(strerror(errno)); exit(1); } } int main(int argc, char** argv) { printf("usage : %s <port,default is 8888>\n",argv[0]); printf("tcp-server...enter\n"); unsigned char* uart_port="/dev

I'm trying to declare a C++ variable that takes up zero bytes. Its in a union, and I started with the type as int[0]. I don't know if that is actually zero bytes (although sizeof(int[0]) was 0). I need a better way to declare a 0 byte type, and hopefully one that can be typedefed to something like nullType or emptyType. The variable is in a union, so in the end memory is reserved anyway. I tried void on the off chance it would work, but C++ complained. I'm using Ubuntu 10.10, with a current version of the kernel, and an up-to-date GCC. Here's the union: union RandomArgumentTypesFirst { uint

最小生成树 给你一个无向带权连通图，每条边是黑色或白色。让你求一棵恰好有need条白色边的权值和最小的生成树。题目保证有解。 对于所有数据，V,E<=100000，c为[1,1000]中的正整数。 题解 可以知道恰好选到need条白边就是最优的，考虑给所有白边加上一个值，随着值的增大，在生成树中的白边越少，所以可以二分。 取最后一次满足条件的值。 排序的时候，对于相同值的边白边优先。 #include<cstdio> #include<iostream> #include<algorithm> using namespace std; const int maxn=100005; int n,m,need; int fa[maxn],sum,cnt; struct edge{ int x,y,c,val; bool operator < (const edge a) const { if(val==a.val) return c<a.c; return val<a.val; } }e[maxn],cy[maxn]; template<class T>inline void read(T &x){ x=0;int f=0;char ch=getchar(); while(!isdigit(ch)) {f|=(ch=='-');ch=getchar();} while(isdigit

I'm converting some code from C# to VB.NET. I have the following line in C# var bytes = new byte[password.Length * sizeof(char)]; Looking on MSDN it appears that VB.NET does not seem to have the sizeof operator. I understand there is a Marshal.SizeOf but further MSDN documentation states that the value returned can be different to that of sizeof . Can anybody help? Is there an equivalent statement in VB.NET? Additional Information My aim is to convert a password into an array of bytes which I can then hash and then either store in a database or compare to a previously stored hash. But I don't

For various reasons, I have some structs I want to force to be specific sizes (in this case 64 bytes and 512 bytes). Both however, are below the somewhat below the sizes I want them to be. Is there anyway for me to tell the compiler to set them to these specific sizes and pad with zeros, or would I be best off just declaring an array inside the struct that makes up the excess space so that it aligns on the size I want? You can use a union. struct mystruct_s { ... /* who knows how long */ }; typedef union { struct mystruct_s s; unsigned char padding[512]; } mystruct; This will ensure the union