关于格式:
1. ,空 ;空 二元操作符前后留空: 空=空 关键词+空: if ()
2. 边写代码边写注释是好习惯;
3. if ( NULL == ptr) 写法比较好;
提供readme 使用方法;
文件头格式:
/***********************************************************************************
# Filename:
# Description:
# Version: 1.12
# Compiler: GCC.2.95
# History:
2007.1.1 Created by aaa
2007.2.5 Modified by bbb
*/
/****************************************Copyright (c)**************************************************
** XXXXX Development Co.,LTD.
**
**
**--------------File Info-----------------------------------------------------
** File name: xxxx.c
** Last modified Date:
** Last Version:
** Descriptions:
**
**--------------------------------------------------------------------------
** Created by:
** Created date:
** Version: 1.0
** Descriptions: The original version
**
**--------------------------------------------------------------------------
** Modified by:
** Modified date:
** Version:
** Descriptions:
**
********************************************************************************************************/
函数头格式:
/***********************************************************************************
# Function Name:
# Description:
# Parameters:
# Return Value:
# Note:
*/
/*********************************************************************************************************
** Function name:
** Descriptions:
** Input: Parameter: Parameter string
** PLen: Parameter string length
** Output: TRUE: OK
** FALSE: NOT OK
** Created by:
** Created Date:
**--------------------------------------------------------------------------
** Modified by:
** Modified Date:
**--------------------------------------------------------------------------
********************************************************************************************************/
scanf的应用: int m; scanf("%d", &m); char a[10]; scanf(" %s", a);
scanf ( "%s%d", p->name, p->age); 输入时一般用空格分开2个数据项;
struct mystruct *p = NULL; 初始化时置NULL比较安全;
内存malloc, free函数在
库;
void strcopy( char *s, char *t)
{
while ( *s++ = *t++)
;
}
void strcomp( char *s, char *t)
{
if ( ; *s == *t; s++, t++)
if ( *s == '\0')
return 0;
return *s - *t;
}
二叉数, 遍历顺序:
前序: 中左右 中序: 左中右 后序: 左右中
闰年的条件: ( year % 4 == 0 && year % 100 ! = 0) | | year % 400 == 0
转为整型数据: atoi( argv[1]) 转为浮点数据: atof(argv[2])
库编译时要加上gcc . . . -lm
周全的做法是检查输入参数的个数, 然后再使用参数;
下标循环问题的解决: i = (i + 1) % N
char *str; str = (char *) malloc (sizeof(char) * 50); free(str);
一个变量的生命周期: 定义, 初始化, 读写值, 销毁;
任何数不作特别说明都是有符号的;
printf ( " -3 0x%x %u %d\n", -3, -3, -3);
main() {}别把子程序包进;
原码, 补码: 原码就是在绝对值的最高位由0改1得到的, 补码就是由原码除去最高位的部分取反加1得到的.
计算机里存储数据的补码, -1在32bit计算机里就是0xFFFFFFFF;
给某位置0, data & ~( 1 << p);
if ( 0 ==strcmp ( type, " %x" ))字符串比较 if( 'z' ==type)字符比较 strstr()查找字符串;
函数中return之后的语句不被执行;
递归的终止条件是不再调用自身;
void func(void) 定义时括号里的void应加上;
sqrt (double t) 参数需要double型;
sort链表应采取的办法: 从前面往后推进, tail从后往前推进, 相邻交换节点;
删除链表节点要free(ptr);
关于链表的操作:
在头节点后面插入: item->next = head->next; head->next = item;
双向链表的删除:
delete_node ( struct node *b)
{
if ( NULL ! = b->prev)
b->prev->next = b->next;
if (NULL ! = b->next)
b->next->prev = b->prev;
}
交换a, b的值有种方法: a = a + b; b = a - b; a = a - b;
MST最小生成树 Minimum Spanning Tree
树: 具有n个节点, n-1条边.
排序算法: 选择排序, 插入排序, 快速排序, 归并排序, 冒泡排序, shell希尔排序
查找算法: 折半查找(有序序列) O ( lg N), 逐个查找O( N) 其他>>>>????
sentry哨兵技术???
xgraph: /usr/local/bin/xg
#!/bin/sh
xgraph -geometry 800x600+100+50 -bb -tk -p -bg white $@
. /mst | xg
. /freuecy < makefile | ptree
/usr/local/bin/ptree
管道与重定向: 管道可以层层传递, 而重定向就导向结束;
程序的结构化: 分函数; 模块化: 分文件;
形参: int func(int a); 无名形参: void push(double); 实参: func(15);
int (*day) [13] 指向整型数组的指针；
int * day[13] 整型指针的数组;
void *comp( ) 函数返回类型;
void (*comp) ( ) 函数指针; 一般用于回调用户定制的函数;
函数名是函数的地址, 就类似数组名; 函数指针的引用: (* comp)( );
while (--argc) printf ( "%s\n", *++argv);
(*++argv) [0] ==>argv[1][0];
*++argv[0] ==>argv[0][1];
优先级问题:
aa->zz . x 从左向右结合;
2 << 7 >> 2 从左到右处理;
top++ 先用值, 再++;
从右到左的运算符有:
! ~ ++ -- + - * & (type) sizeof
+= -= *= /= %= &=
? :
指针之间的加法是非法的, 所以求中值需要这样: p1 + (p2 - p1)/2;
MST查找最短路径:
st[] 存放已经上树的节点/双亲节点; st[] = -1是未上树的部分;
fr[] 未收入树的节点中, 与树最近的节点号;
wt[] 未收入树的节点中, 与树最近的距离值;
. h里面一般是函数申明及类的定义, 也有部分宏定义.
快速排序qsort():
int partition ( int l, int r)
{
int i= l +1, j = r;
do{
while ( i<=j && v[i]<=v[j] ) i++;
while ( i<=j && v[l]<=v[j] ) j--;
swap ( i, j); //若i或j越界, 均会发生一次多余swap;
}while ( i <= j);
swap ( i, j); //恢复i, j的位置
swap ( l, j); //j最终会 停留在<=v[l]的数据上, 交换符合左小右大的大原则;
return j;
}
对有序表, 择半查找:
定义全局V[N], 返回下标值;
int bisearch( int x, int l, int r)
{
int m = ( l + r)/2;
if ( l > r) return -1;
if ( x > V[m] ) return bisearch( x, m+1, r);
if ( x < V[m] ) return bisearch( x, l, m-1);
return m;
}
对无序表排序, 希尔排序:
void shellsort(void)
{
int gap, i, j, temp;
for ( gap = N/2; gap > 0; gap /= 2)
for ( i = gap; i < N; i++)
for ( j=i-gap; j>=0 && V[j]>V[j+gap]; j-=gap)
temp = V[j], v[j] = V[j+gap], V[j+gap] = temp;
}
递归调用:
putchar若在if后面, 则输出顺序正确; 若放在if前面, 则输出顺序反了;
void printd ( int n)
{
if ( n / 10 ) printd ( n / 10 );
putchar ( n % 10 + '0');
}
一些C++例程：
/*mystring.h
* this is a string class
*/
#include
#include
using namespace std;
/*MyString class*/
class MyString
{
friend ostream& operator<<(ostream&, const MyString&);
friend MyString operator+(const MyString&, const MyString&);
public:
MyString(const char*);
MyString(const MyString&);
~MyString(void);
MyString& operator=(const MyString&);
int length(void) const;
bool isEmpty(void) const;
private:
char *data;
int len; //don't include '\0'
};
/*construct function*/
MyString::MyString(const char* str="")
{
char* cp;
const char* cs;
len = strlen(str);
data = new char [len + 1];
cp = data;
cs = str;
while (*cs)
*cp++ = *cs++;
*cp = '\0';
}
MyString::MyString(const MyString& mstr)
{
char* cp;
char* cs;
len = mstr.len;
data = new char [len + 1];
cp = data;
cs = mstr.data;
while (*cs)
*cp++ = *cs++;
*cp = '\0';
}
MyString::~MyString(void)
{
delete [] data;
}
MyString& MyString::operator=(const MyString& mstr)
{
char* cp;
char* cs;
if (this == &mstr) return *this;
delete [] data;
len = mstr.len;
data = new char [len + 1];
cp = data;
cs = mstr.data;
while (*cs)
*cp++ = *cs++;
*cp = '\0';
return *this;
}
int MyString::length(void) const
{
return len;
}
bool MyString::isEmpty(void) const
{
if (len == 0)
return true;
else
return false;
}
ostream& operator<<(ostream& o, const MyString& mstr)
{
return o << mstr.data;
}
MyString operator+(const MyString& ma, const MyString& mb)
{
char *cp, *cs;
MyString addrs;
addrs.len = ma.len + mb.len;
delete [] addrs.data;
addrs.data = new char [addrs.len+1];
cp = addrs.data;
cs = ma.data;
while (*cs)
*cp++ = *cs++;
cs = mb.data;
while (*cs)
*cp++ = *cs++;
*cp = '\0';
return addrs;
}
//main.cpp
#include "mystring.h"
int main()
{
MyString str("hello");
MyString str1 = str;
cout<<"Length of str1: "< cout<<"Value of str1: "<
MyString str2 = "";
cout<<"Is str2 empty? "<<(str2.isEmpty()?"true":"false")<
str2 = " world";
cout<<"Now value of str2: "<
cout<<"Now value of str: "< cout<<"Value of another expression: "< cout<<"Value of yet another expression: "<<"Hello," + str2<
MyString str3 = str1 + str2;
cout<<"Value of str3: "<
return 0;
}
/*list.cc
*class inherit
*/
#include
#include
using namespace std;
class List
{
protected:
int *list_;
int n_;
public:
List(int n=10) : n_(n)
{
list_ = new int [n_];
srand(time(NULL));
for (int i=0; i list_[i] = rand() % n_;
}
~List()
{
delete [] list_;
cout << "List dtor" << endl;
}
virtual void show() const
{
for (int i=0; i cout << list_[i] << ' ';
cout << endl;
}
};
class OList : public List
{
private:
void swap(int &a, int &b)
{
int c;
c = a;
a = b;
b = c;
}
void Qsort(int l, int r)
{
if (l>=r) return;
int k = partition(l, r);
Qsort(l, k-1);
Qsort(k+1, r);
}
int partition(int l, int r)
{
int i, j;
for (i=l+1, j=l; i<=r; i++)
if (list_[i] swap(list_[i], list_[++j]);
swap(list_[l], list_[j]);
return j;
}
public:
OList(int n=8) : List(n)
{
}
virtual void show()
{
Qsort(0, n_-1);
for (int i=0; i cout << list_[i] << ' ';
cout << endl;
}
};
const int N = 8;
int main()
{
List l(N);
l.show();
sleep(1);
OList o(N);
o.show();
return 0;
}
/*mymatrix.cc
*matrix deal
*/
#include
#include
using namespace std;
class Matrix
{
double **matrix_;
int n_;
public:
Matrix(int n=10) : n_(n)
{
matrix_ = new double* [n_];
for (int i=0; i matrix_[i] = new double [n_];
srand(time(NULL));
for (int i=0; i for (int j=0; j matrix_[i][j] = rand()%10;
}
~Matrix()
{
for (int i=0; i delete [] matrix_[i];
delete [] matrix_;
}
Matrix(const Matrix &m)
{
cout << "copy" << endl;
n_ = m.n_;
matrix_ = new double*[n_];
for (int i=0; i {
matrix_[i] = new double [n_];
for (int j=0; j {
matrix_[i][j] = m.matrix_[i][j];
}
}
}
Matrix& operator=(const Matrix &m)
{
int i, j;
cout << "=" << endl;
for (i=0; i delete [] matrix_[i];
delete [] matrix_;
matrix_ = new double*[m.n_];
for (i=0; i {
matrix_[i] = new double [m.n_];
for (j=0; j {
matrix_[i][j] = m.matrix_[i][j];
}
}
return *this;
}
void transpose()
{
Matrix temp(n_);
for (int i=0; i {
for (int j=0; j {
temp.matrix_[i][j] = matrix_[j][i];
}
}
for (int i=0; i {
for (int j=0; j {
matrix_[i][j] = temp.matrix_[i][j];
}
}
}
/*
Matrix& operator+\
(const Matrix &m)
{
cout << "+" << endl;
for (int i=0; i for (int j=0; j matrix_[i][j] += m.matrix_[i][j];
return *this;
}*/
friend Matrix operator+\
(const Matrix &m1, const Matrix &m2);
friend Matrix operator*\
(const Matrix &m1, const Matrix &m2);
friend ostream &operator<<\
(ostream &o, const Matrix &m);
};
Matrix operator*\
(const Matrix &m1, const Matrix &m2)
{
cout << "*" << endl;
Matrix temp(m1.n_);
for (int i=0; i {
for (int j=0; j {
temp.matrix_[i][j] = 0;
for (int k=0; k {
temp.matrix_[i][j] +=\
m1.matrix_[i][k] * m2.matrix_[k][j];
}
}
}
return temp;
}
Matrix operator+\
(const Matrix &m1, const Matrix &m2)
{
cout << "+" << endl;
Matrix temp(m1.n_);
for (int i=0; i {
for (int j=0; j {
temp.matrix_[i][j] = 0;
temp.matrix_[i][j] =\
m1.matrix_[i][j] + m2.matrix_[i][j];
}
}
return temp;
}
ostream &operator<<\
(ostream &o, const Matrix &m)
{
for (int i=0; i {
for (int j=0; j {
o << m.matrix_[i][j] << " ";
}
o << endl;
}
return o;
}
const int N = 5;
int main()
{
Matrix m(N);
sleep(1);
Matrix n(N);
cout << "use = or copy?" << endl;
Matrix k=n+m;
cout << m << endl;
cout << n << endl;
cout << k << endl;
k = m + n;
cout << m + n << endl;
cout << m * n << endl;
m.transpose();
cout << m << endl;
return 0;
}
/*stack.cc*/
#include
using namespace std;
class Stack
{
int *stack_;
int n_;
int top_;
public:
Stack(int n=1024) : n_(n)
{
//stack = malloc(n*sizeof(int));
stack_ = new int [n_];
top_ = 0;
}
~Stack() { delete [] stack_;}
Stack(const Stack &S)
{
n_ = S.n_;
top_ = S.top_;
stack_ = new int [n_];
for (int i=0; i stack_[i] = S.stack_[i];
}
Stack operator=(const Stack &S)
{
n_ = S.n_;
top_ = S.top_;
stack_ = new int [n_];
for (int i=0; i stack_[i] = S.stack_[i];
return *this;
}
void push(int item);
int pop(void);
bool empty() const;
};
void Stack::push(int item)
{
stack_[top_++] = item;
}
int Stack::pop(void)
{
return stack_[--top_];
}
bool Stack::empty() const
{
return top_ == 0;
}
const int N = 10;
int main()
{
Stack S1;
for (int i=0; i {
S1.push(i);
}
/*
for (int i=0; i {
cout << S1.pop() << endl;
}*/
Stack S2(S1);
while(!S2.empty())
{
cout << S2.pop() << endl;
}
return 0;
}
信息点滴:
! ! ! 结构体, 共用体, 枚举
! ! ! BSTree Hash Binary-search
debian浏览器位置不对, 注销重新登录即可; 菜单隐藏ctrl + M;
gcc --version查版本号;
EOF = -1; 在stdio.h中定义;
wc test.c 统计数据;
float, double用%d打印出来是乱数;
, 运算符是从左往右结合. 右边的值是结果. 如: i = 1, i =2;
ctrl+D 是退出shell;
sudo apt-get install gnome;
x =3, y=2; x += y+= 1; 从右往左运算;
palindrome: Madam i'm Adam==>madamimadam deed level
ps -aux, netstat -apn;
ctrl+ 退格 删除当前行;
*p++ == *(p++) *++p == *(++p)
堆栈段只能读写不能执行;
拼音输入法不稳定, 也许输入法重装可以;
RTFM--->read the fine(f**k) mannual
CGDB ESC由下到上, i由上到下, 但scanf不能输入;
哲学家用餐问题: 5个哲学家, 每人一根筷子, 每人有三种状态: 思考 吃 饥饿;
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