C 和 C++ 一些基础

位运算:

Part1:

#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    //unsigned char per byte that contain 00000000 - 11111111
    unsigned char a=2;  // bin->0000 0010
    unsigned char b = ~a; //~(0000 0010) result:(1111 1101) or 253
    printf("%d
",b);

    unsigned char c=3; //0000 0011
    unsigned char d=2; //0000 0010
    printf(" & %d
",c&d); // c&d -> 0000 0010 : 2

    printf(" | %d
",c|d); // c|d -> 0000 0011 : 3

    
    //十六进制->十进制 hexadecimal(hex)->base10
    int d_hex = 0xA3F;
    //A-..-F (10-15)
    //0xA3F -> A3F -> 10*16^2 + 3*16^1 + 15*16^0 = 2623
    printf("0xA3F : %d
",d_hex); // 2623

    int d_hex_zero = 0x000; //0*16^2 + 0*16^1 + 0*16^0 = 0
    printf("0x000 : %d
",d_hex_zero);

    int d_hex_1 = 0x001; //0*16^2 + 0*16^1 + 1*16^0 = 1
    printf("0x001 : %d
",d_hex_1);

    int d_hex_2 = 0x011; //0*16^2 + 1*16^1 + 1*16^0 = 17
    printf("0x001 : %d
",d_hex_2);
    
    return 1;
}

Part2:

#include <iostream>

using namespace std;

int main()
{
    // int is 32 bit
    int a = 10; //00000000 00000000 00000000 00001010  0*2^0 + 1*2^1 + 0*2^2 + 1*2^3 = 10
    int b = 5;  //00000000 00000000 00000000 00000101  1*2^0 + 0*2^1 + 1*2^2 + 0*2^3 = 5
    int c = a | b ; // 00000000 00000000 00000000 00001111 1+2+4+8 = 15
    cout << c <<endl;
    int d = c|0xFF;  //hex: 0xFF = 15*16^1 + 15*16^0 = 255  bin:255-> 1111 1111
    cout << d <<endl;


    // ^
    int e = a ^ b; //00000000 00000000 00000000 00001111 1*2^3 + 1*2^2 + 1*2^1 + 1*2^0 = 15
    cout << e <<endl;

    // swap a b
    // a 00000000 00000000 00000000 00001010
    // b 00000000 00000000 00000000 00000101

    a = a ^ b ; // a->00000000 00000000 00000000 00001111
    b = b ^ a ; // b->00000000 00000000 00000000 00001010
    a = a ^ b ; // 00000000 00000000 00000000 00000101

    cout << "after swap a,b  a:" << a << "	" << "b:"<<b <<endl;
    return 0;
}

C语言的几个输入输出函数

#include <stdio.h>

getchar(),putchar()

scanf(),printf()

1->getchar()与scanf()唯一的区别是getchar()不会跳过' '或者空格,例如如下

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int ch;
    int a,b;
    printf("enter a char ,enter to quit
");
    while((ch=getchar()) != '
' )
    {
        if (scanf("%d %d",&a,&b)!=2)
            break;
        printf("you enter the %c %d %d
",ch,a,b);
        // getchar();//the ch a b enter complete will leave a '
'
        while(getchar() != '
') // GNU BOOK always use this
        {
            continue;
        }
        printf("PLEASE ENTER ANOTHER CHAR 
");
    }

    exit(0);
}

如果没有while循环中的while(getchar() != ' ') ，那么程序输入一轮直接结束，原因是scanf()会把回车 放到输入队列。所以要剔除输入的回车

2->如何确定输入类型

scanf()返回值是其成功读入的项目个数。比如scanf("%d %d",&a,&b)==2

 如下面代码，如果输入q,则state=0

int main()
{
    int input;
    int state = scanf("%d",&input);
    printf("state = %d,and input value is %d,",state,input);
    exit(0);
}

输入输出大集合:

 char temp[81];
    printf("Please enter your first name
");
    // STDIN
    //scanf("%s",temp); // jump backspace
    //fscanf(stdin,"%s",temp); // jump backspace
    fgets(temp,81,stdin); // do not jump backspace
    //gets(temp);  // do not jump backspace

    // STDOUT
    //printf("You enter the strings -> : %s
",temp);
    //fprintf(stdout,"You enter the strings -> : %s
" ,temp);
    //fputs(temp,stdout);
    puts(temp);

    // CHAR putchar() getchar()

    //getc(FILE*) putc(char,FILE*)
    FILE *in;
    FILE *out;
    in = fopen("test.txt","r");
    if(in==NULL){return;}
    out = fopen("test.txt","w");
    if(out==NULL){ return;}
    int ch;
    while((ch=getc(in))!=EOF) // COPY DATA PER CHAR
    {
        putc(ch,out);
    }

宏定义：

#include <stdio.h>
#define PSQR(x) printf("Value squre of "#x" is %d 
",(x*x));
#define XNAME(n) x##n

#define SIZE "HOUDINI"

#ifdef SIZE // if define the SIZE
    #define SIZE "MAYA"
#endif

#ifdef __GNUC__  //if define the __GUNC__
    #define HOUDINI 2
#else
    #define HOUDINI 3
#endif

#ifndef __SIZEOFINT__  // becuase __SIZEOFINT__ do not define,that "if not define the __SIZEOFINT__"
    #define __SIZEOFINT__ sizeof(int)  // so can arrive this code
#endif


#define NOFLOAT 1

#if NOFLOAT == 1 //check NOFLOAT equal 1,then #include<float.h>
#include <float.h>
#elif NOFLOAT == 2
#include <typeinfo.h>
#elif NOFLOAT == 3
#include <typeinfo.h>
#else
#include <stdarg.h>
#endif

#if defined(NOFLOAT)  // if define NOFLOAT  ------ same as #ifdef NOFLOAT
    #define A 2
#endif

int main(int argc, char *argv[])
{
    printf("Hello World!
");
    PSQR(2*4);

    char name[20];
    fprintf(stdout,"enter the name
");
    fgets(name,20,stdin);

    int i=0;

    return 0;
}

定义一个简单的宏：

#define GARRSERT(EXP) 
{
    if(EXP != 1)
{
    printf("Assert expression "#EXP " ERROR %s IN %d line 
",__FILE__,__LINE__);
    exit(0);
}
}

GARRSERT(3>5);

strycpy strlen

#include <stdio.h>
#include <stddef.h>
void gstrcpy(char *dst,char const *str);
void gstrcpy2(char *dst, char const *str);
size_t gstrlen(char *str);
int main()
{
    char *src = "houdini";
    char dst[8]={''};
    gstrcpy(dst,src);
    printf("get final str %s 
" , dst);
    return 0;
}

void gstrcpy(char *dst, char const *str)
{
    while( 1 )
    {
         *dst++ = *str++;
        if(*dst != '')
            break;
    }
}
void gstrcpy2(char *dst, char const *str)
{
    while((*dst++ = *str++) !='');
}
size_t gstrlen(char *str)
{
    int length;
    for(length=0;*str++ != '';length+=1);
    return length;
}

3,C++ 标准输入cin, getline(),cin.get() ;

#include <iostream>
#include <cstring>
using namespace std;

#define FLUSH_BUFFER()
while(cin.get()!='
') 
{
continue;
}


int main()
{
    
    char info[100];

    cout << "
**use cin>>info
";
    cin >> info;   // read a word,and leave other to the buffer ,include '
',but no whitespace
    cout << "==use cin>>info: " <<info << "  It's Length: " <<strlen(info)<<endl;

    FLUSH_BUFFER();


    cout << "
**cin.getline(info,100)
";
    cin.getline(info,100); // read a line,discard '
'
    cout << "==use cin.getline(info,100):" << info <<endl;

    cout << "
**cin.get(info,100)
";
    cin.get(info, 100); // read a line ,but leave the '
' to buffer
    cout << "==use cin.get(info,100): " << info << std::endl;


    FLUSH_BUFFER();


    cout<< "
**next use the String
";
    string stuff;
    cin>>stuff; //read a word ,leave 
,but no whitespace
    cout << "==use cin>>stuff: " << stuff << std::endl;

    FLUSH_BUFFER();

    cout<< "
**next use the getline(cin.stuff)
";
    getline(cin,stuff);   // read a line,discard '
'
    cout << "==use getline(cin,stuff) " << stuff << std::endl;
    
    char fname[10];
    string lname;
    cin >> fname; // if input size > 9 , could be a problem
    cin >> lname; // can read long  long word
    
    // C++ Style :
    operator>>(cin,fname);
        
    

    return 0;
}

4,

(1)字符串分析,函数指针)

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <vector>
#include <omp.h>
#include <sstream>
#include <string.h>
#include <algorithm>
using namespace std;

namespace PARSE_STRING 
{


    inline int start_with(string &input,string startwith)
    {
        if(startwith.size()>input.size())
        {
            return 0;
        }
    
        int state = 0;
        for(int i=0;i<startwith.size();i++)
        {
            if(input[i]!=startwith[i])
            {
                state = -1;
            }
        }
        if(state==0)
        {
            return 1;
        }
    }

    inline string int_to_str(int value)
    {
        char str[10];
        sprintf(str,"%d",value);
        string final(str);
        return final;
    }
    
    inline string str_to_pad(string str,int pad)
    {
        string prefix="0000000";
        string cnt_str = prefix + str;
        string final = cnt_str.substr(cnt_str.size()-pad,cnt_str.size());
        return final;
    }
}
namespace GLY_FUNCTION_POINTER
{    
    void test()
    {
        cout << "test with no arguments
";
    }
    void test2(int a)
    {
        cout << "test with one arguments "<< a <<"
";
    }
    void* test3()
    {
        cout << "test with no argumetens and return pointer"<<"
";
        int a =10;
        return (void*)&a;
    }
    void *test4(int b)
    {
        cout <<"test with one arguments and return pointer" << "
";
        return (void*)&b;
    }
    
    
    void test_pointer_func()
    {
        typedef void (*pf)();
        pf _func_01 = test;
        _func_01();
    
        typedef void (*pf_one)(int);
        pf_one _func_02 = test2;
        _func_02(2);
    
        typedef void * (*pf_sce)();
        pf_sce _func_03 = test3;
        cout << *((int*)_func_03()) << endl;
    
        typedef void * (*pf_sce_one)(int);
        pf_sce_one _func_04 = test4;
        cout <<  *((int*)_func_04(5)) <<endl;
    }

}


void heap_test()
{
    int ia[9]={0,1,2,3,4,8,9,3,5};
    vector<int> ivec(ia,ia+9);
    for(int i=0;i<ivec.size();i++)
    {
        cout << "i :" << i << " -> value:" << ivec[i] << endl;
    }
    make_heap(ivec.begin(),ivec.end());
    cout << "----
";
    for(int i=0;i<ivec.size();i++)
    {
        cout << "i :" << i << " -> value:" << ivec[i] << endl;
    }
    cout << "----
";
    pop_heap(ivec.begin(),ivec.end());
    for(int i=0;i<ivec.size();i++)
    {
        cout << "i :" << i << " -> value:" << ivec[i] << endl;
    }
}

void convert_data()
{

    int a = 10;
    void *data = (void*)&a;
    int b = *(int *)data;
    cout << b <<endl;

}

void reverse_the_container()
{
    vector <int> aaa;
    aaa.push_back(1);
    aaa.push_back(2);
    aaa.push_back(3);

    //std::reverse(aaa.begin(),aaa.end());  // this is use the algorithm.h ,aaa will changed
    //cout << aaa[0] <<endl;

    for(vector<int>::const_reverse_iterator iter=aaa.rbegin();iter!=aaa.rend();++iter)  // aaa do not change
        cout<<*iter<<endl;


}
void transfer_data(void *data,int length)
{

    for(int i=0;i<length;i++)
    {
        cout << ((int*)data)[i] << endl;
    }
}



struct myarray
{
    vector <int> data;
};

void transfer_struct(void *data)
{
    cout<<"transfer_struct "<<data<<endl;
    myarray rh_array = *(myarray*)data;
    for(int i=0;i<rh_array.data.size();i++)
    {
        cout<< rh_array.data[i] << endl;
    }
}

template <typename T>
struct gly_array
{
    vector <T> data_array;
};

template <typename T>
void transfer_struct_template(gly_array<T> rh_array)
{
    for(int i=0;i<rh_array.data_array.size();i++)
    {
        cout<< rh_array.data_array[i] << endl;
    }
}



int main()
{
  myarray _array;
  _array.data.push_back(10);
  _array.data.push_back(11);
  cout<< "main "<<&_array<<endl;
  transfer_struct((void*)&_array);

  cout<< "template ";
  gly_array<int> int_array;
  int_array.data_array.push_back(10);
  int_array.data_array.push_back(11);
  int_array.data_array.push_back(12);
  cout << &int_array<<endl;
  transfer_struct_template(int_array);

}

(2)point 

namespace test_struct_define 
{
    struct Point3d
    {
        float x;
        float y;
        float z;
    };

    #define XSET(P,xval,yval,zval)
    {
        P.x=xval;
        P.y=yval;
        P.z=zval;
    }

    inline ostream& operator <<(ostream &os,const Point3d &pt)
    {
        os << "X:VALUE->"<<pt.x << " Y:VALUE->"<< pt.y << " Z:VALUE->" <<pt.z<<endl;
        return os;
    }

    int main()
    {
        Point3d pt;
        XSET(pt,1,2,3);
        cout<< pt <<endl;
    }


}

template <typename T>
class GLY_POINT_3d
{
public:
    GLY_POINT_3d(T x=0.0,T y=0.0,T z=0.0):_x(x),_y(y),_z(z)
    {
    }

    T x() const
    {
        return _x;
    }
    T y() const
    {
        return _y;
    }
    T z() const
    {
        return _z;
    }

    friend ostream&operator<<(ostream &os,const GLY_POINT_3d <T> &pt)
    {
        os<< pt.x()<< " "<< pt.y()<<" " << pt.z();
        return os;
    }


    T &operator [](int index)
    {
        assert(index<3);
        if(index==0)
        {
            return _x;
        }
        if(index==1)
        {
            return _y;
        }
        if(index==2)
        {
            return _z;
        }
    }
private:
    T _x;
    T _y;
    T _z;
};
int main()
{
    GLY_POINT_3d <int> pt(1,2,3);
    cout << pt<<endl;
    cout << pt[0] <<endl;
    cout << pt[1] <<endl;
    cout << pt[2] <<endl;


}