wangzhicheng2013的专栏

指向函数返回值与局部作用域

stderror_r有bug

使用C语言实现接水问题

用C语言实现字符串编码

使用C语言代码生成某年某月日历

多条件变量应用--传送与搬运问题

栈溢出检测小结

建立在相似三角形 对应边比平方等于面积比 证明勾股定理

#include <stdio.h>#include <stdlib.h>#include <string.h>typedef struct _Template{ int title; int font; int lineDistance; void (*operate)(struct _Template *pTemplate);} Template;void operate(struct _Template *pTempla.

#include <stdio.h>#include <stdlib.h>typedef struct _BodyBuilder{ void (*play)();} BodyBuilder;typedef struct _BailPlaying{ void (*play)();} BailPlaying;typedef struct _PlayRequest{ int type; void *pPlaying;} PlayRequ.

#include <stdio.h>#include <stdlib.h>typedef struct _Coffee{ void (*have_coffee)();} Coffee;typedef struct _Tea{ void (*have_tea)();} Tea;void have_black_coffee(){ printf("have black coffee!\n");}void have_white_coffee(.

#include <stdio.h>#include <stdlib.h>typedef struct _shoes{ int type; void (*produce_shoes)(struct _shoes *);}myShoes;void produce_leather_shoes(myShoes *pshoes) { if (NULL != pshoes) { printf("produce the leather.

#include <stdio.h>#include <stdlib.h>#include <assert.h>#define MAKE_INSTANCE 1#define FREE_INSTANCE 0typedef struct { int age; char name[12];} record;static record * operate_instance(int flag) { static record *pReco.

#include <stdio.h>typedef char * PSTR;int main() { char string[4] = "abc"; const char *p1 = string; const PSTR p2 = string; p1++; //p2++; // 编译出错 *p2 = 'd'; printf("%s\n", string); return 0;}...

#include <stdio.h>struct bit1 { unsigned a:20; unsigned b:6; unsigned c:2;}test_bit1;struct bit2 { unsigned d:20; unsigned e:6; unsigned f:20;}test_bit2;union UN { unsigned int u; struct { unsigned char a.

#include <stdio.h>#include <string.h>int fun1() { return 1;}int fun2() { return 2;}int fun3() { return 3;}int fun4() { return 4;}struct { char *name; int (*func)();}symtab[] = { "fun1", fun1, "fun2",.

#include <stdio.h>#include <string.h>#define PRINT_SZ(intValue) printf(#intValue" is %zd\n", (intValue));#define STRUCT_MEMBER_OFFSET(type, member) ((char *)&((type *)0)->member - (char *)0)/*struct Test { char a; short b;.

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <math.h>double my_add(double x, double y) { return x + y;}double my_sub(double x, double y) { return x - y;}double my_mul(double x, double y) { re.

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <stdarg.h>__attribute((constructor)) void before_main(){ printf("%s\n", __FUNCTION__);}__attribute((constructor)) void after_main(){ printf("%s\n", __.

#include <stdio.h>int main() { typedef char *charp; // charp是一种类型即char * const charp p = "123"; // const仅仅修饰p 这行代码与const int p = 123;类似 都表明p是一个常量 *p = '1'; // 无编译错误 说明上述代码确实不能达到const char *p = "123"的效果 但运行会出现段错误 因为它企图改.

#include <stdio.h>int main() { const char c = 'X'; // c为常量 不能修改 char *p1; // 危险的未赋值的悬挂指针 const char **p2 = &p1; // 会有编译警告 因为=两边指针类型不同 *p2 = &c; // 修改p2指向的地址 这导致p1被修改为&c *p1 = 'Y'; .

#include <stdio.h>#define DEBUG printf("file:%s, line:%d", __FILE__, __LINE__), printfint main() { DEBUG("X is %d\n", 100); // 宏替换后("X is %d\n", 100);会写在printf最后 return 0;}

int main() { char *p = (char *)malloc(10); char *newp = (char *)realloc(p, 20); // realloc不能保证newp与p指向同一块内存 if (newp) { p = newp; } free(p); return 0;}上述代码，如果注释4~6行将引发内存泄漏，free只释放了p生成的内存空间，而realloc生成的内存没有释放。...

#define ROW 2#define COL 3void fun(int **p) { int i = 0; int j = 0; for (;i < ROW;i++) { for (j = 0;j < COL;j++) { printf("%d\n", p[i][j]); } }}int main() { int a[ROW][COL] = { { 1, 2, 3}, { 4, 5, .

#include <stdio.h>#include <stdlib.h>#include <string.h>// fun1使用方式1创建n行m列动态二维整数数组void fun1(int n, int m) { int **array1 = (int **)malloc(n * sizeof(int *)); int i = 0; int j = 0; for (;i < n;i++) { array1[.

int a[3] = { 1, 2, 3 };int (*p)[3] = &a; // 赋值正确，p保存指向a的指针，是一个二维指针p++; // 指针跑飞*((*p) + 1) = 10; // stack smashingint b[2][3] = { { 1, 2, 3 }, { 1, 2, 3 } };int (*p1)[3] = b; // 赋值正确，p1保存指向b的指针，.

一 检测插件概述1.代码位置：snort源码src/detection-plugins2.作用：snort规则体可定义关键词，如对于ICMP协议的itype，icode等，这些关键词及其参数都会被检测插件解析，并调用检测插件相关函数进行处理。如在规则体定义itype:3，那么检测插件会根据输入分组packet结构的icmp协议的type和规则里itype进行比较操作。二 检测插件Setup每个检测插件都有Setup函数，例如sp_icmp_type_check.c中的SetupIcmpTyp

int a = 1, b = 0;// (a > b ? a : b) = 100; // 编译错误 ?:不能作为左值*(a > b ? &a : &b) = 100; // 正确

#include <iostream>#include <algorithm>#include "count_sort.hpp"int main() { static const int LEN = 10; int loop = 10000000; for (int i = 0;i < loop;i++) { int array[LEN] = { 1, 0, 1, 2, 4, 10, 11, 13, 2, 5 }; .

一 会话控制块session control block含义 scb是snort用来保存一次完整会话信息，包括会话Key，会话首次时间，会话最终时间，会话过期时间，ttl信息，snort策略ID，服务器端IP，客户端IP，服务端通信端口，客户端通信端口，协议，MAC地址，客户端请求字节数，服务端响应字节数，会话ID，客户端请求包数，服务端响应包数等，其定义在snort源码preprocessors/Session/session_common.h：typedef struct _Sessio..

1.socket ipc通信优势：不需要经过网络协议栈；不需要打包拆包；不需要计算校验和；不需要维护序号和应答等；2.sockaddr_un结构：#define UNIX_PATH_MAX 108 struct sockaddr_un { sa_family_t sun_family; /* AF_UNIX */ char sun_path[UNIX_PATH_MAX]; /* pathname */};3.用法：服务端与客户端通过本地socket文件进行通

1.pcap_dispatch和pcap_loop使用回调函数结构都一样：static void process_packet(u_char *user, struct pcap_pkthdr *pHeadr, u_char *pkt_data) { // 如果process_packet定义在类中，那么必须以static修饰}2.pcap_dispatch和pcap_loop函数参数都一样：int pkts_read = -1; // 让libpcap一直抓包，如果pkts

gcc从4.1.2提供了__sync_*系列的built-in函数，用于提供加减和逻辑运算的原子操作。可以对1,2,4或8字节长度的数值类型或指针进行原子操作，其声明如下：type __sync_fetch_and_add (type *ptr, type value, ...)type __sync_fetch_and_sub (type *ptr, type value, ...)type __sync_fetch_and_or (type *ptr, type value, ...)typ

#include <iostream>#include <string>#include <stack>using namespace std;class Solution {public: bool isValid(string s) { int i = 0; int size = s.size(); char ch; char left_bracket; std::st.

#pragma oncetemplate <class T>class single_instance {public: static inline T instance() { static T obj; return obj; }private: single_instance() = default; virtual ~single_instance() = default;};#pragma once#i.

#include <iostream>class Solution {public: double myPow(double x, int n) { if (fabs(x - 1.0) < 0.00000001) { return 1; } if (fabs(x + 1.0) < 0.00000001) { return n % 2 ? -1 : 1; } .

#include <stdio.h>#include <iostream>#include <algorithm>struct TreeNode { int val; TreeNode *left; TreeNode *right; TreeNode(int x) : val(x), left(NULL), right(NULL) { }};TreeNode *root;class Solution {public:.

#include <stdio.h>#include <stdlib.h>#include <time.h>#include <sys/time.h>#include <stdint.h>#include <string.h>#include <sys/socket.h>#include <n...