Some test code designed by myself

The following source code are designed by my self to test some special operation.

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 1. 快速排序法

 

#include"stdio.h"

struct mytype
{
 int wy;
};

void quickSort(int a[],int left,int right)
{
   int i,j,temp;
   i=left;
   j=right;
   temp=a[left];
   if(left>right)
      return;
   while(i!=j)/*找到最终位置*/
   {
      while(a[j]>=temp && j>i)
         j--;
      if(j>i)
         a[i++]=a[j];
       while(a[i]<=temp && j>i)
          i++;
       if(j>i)
          a[j--]=a[i];
        
   }
   a[i]=temp;
   quickSort(a,left,i-1);/*递归左边*/
   quickSort(a,i+1,right);/*递归右边*/
}

int main()
{
 mytype wyh;
 wyh.wy = 1;
    int a[10]={8,2,7,88,6,12,1,9,5};
    int i;
  //  quickSort(a,0,8);
 printf("----->%d,%x/n",sizeof(a),-215);
    /*排好序的结果*/
    for(i=0;i<9;i++)
        printf("%4d",a[i]);
 return 0;
}

----------------------

 

 

2 计算结构体的大小

 

 

#include <stdio.h>
typedef struct {
        char a;
        int b;
        unsigned short c;
        long d;
        unsigned long long e;
        char f;
}A;

struct B{
        char a;
        int b;
        unsigned short c;
        long d;
        unsigned long long e;
        char f;
}__attribute__((aligned));

struct C{
        char a;
        int b;
        unsigned short c;
        long d;
        unsigned long long e;
        char f;
}__attribute__((aligned(1)));

struct D{
        char a;
        int b;
        unsigned short c;
        long d;
        unsigned long long e;
        char f;
}__attribute__((aligned(4)));

struct E{
        char a;
        int b;
        unsigned short c;
        long d;
        unsigned long long e;
        char f;
}__attribute__((aligned(8)));

struct F{
        char a;
        int b;
        unsigned short c;
        long d;
        unsigned long long e;
        char f;
}__attribute__((packed));

int main(int argc, char **argv)
{
        printf("A = %d, B = %d, C = %d, D = %d, E = %d, F = %d/n",
                sizeof(A), sizeof(struct B), sizeof(struct C), sizeof(struct D), sizeof(struct E), sizeof(struct F));
        return 0;
}

--------------------------------

 

#include "stdio.h"

int main(int argc, char * argv[])
{

struct s1
{
   int i: 8;
   int j: 4;
   int a: 3;
   double b;
}__attribute__ ((aligned));

struct s2
{
   int i: 8;
   int j: 4;
   double b;
   int a:3;
}__attribute__ ((packed));

printf("sizeof(s1)= %d/n", sizeof(struct s1));
printf("sizeof(s2)= %d/n", sizeof(struct s2));

 return 0;
}
--------------------

3 看到别人写的一个itos。

 

#include <stdio.h>
#include <math.h>

char *itos(int number)
{
 int  sz;
 char *s = NULL;

 if (number == 0) sz = 1;
 else if (number < 0) sz = (int) log10(-number) + 2;
 else   sz = (int) log10(number) + 1;

 s = new char [sz + 1];

 if (number < 0)
 {
  s[0] = 45;

  for (int i = 0; i < sz-1; i++)
  {
   s[i + 1] = (char) floor(((-number) % (int) pow(10, sz - i - 1)) / pow(10, sz - (i + 1) - 1)) + 48;
  }
 }
 else
 {
  for (int i = 0; i < sz; i++)
  {
   s[i] = (char) floor((number % (int) pow(10, sz - i)) / pow(10, sz - (i + 1))) + 48;
  }
 }

 s[sz] = 0;

 return s;
}

int main()
{
 printf("itos(134)=%s,itos(3421)=%s,itos(-231)=%s/n",itos(134),itos(3421),itos(-231));
 return 0;
}
-------------------

 

 

 

4 something always foget

 

 

------------

 

#include "stdio.h"

int main()
{

 unsigned int const size1 = 2;
 int size4 = 7;
char str1[ size1 ] = {0};
unsigned int temp = 0;
scanf("%d",&temp);
unsigned int const size2 = temp;
char str2[size2 ];
char test[16] = {0};
char str9[size2 ];
printf("addr: str=%x,test=%x,%x/n",str2, test,str9);
printf("%d,%d,%d/n", sizeof(str1),sizeof(str2),sizeof(test));
 return 0;
}
------------------

 

 

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

int main(int argc, char *argv[])
{
 char a[] = "abc";
     char b[] = {'d', 'e', 'f'};

     printf("a slen=%d,b slen=%d/n", strlen(a),strlen(b));
        printf("a = %s,%x, b = %s,%x/n", a,a,b, b);
     printf("asize len = %d, bsize len = %d/n", sizeof(a),sizeof(b));
     return 0;
}
------------

 

 

 

5 有意思的题， 你知道结果么？

 

--

 

#include "stdio.h"
#include "string.h"
int main()
{
    char str[10];
    char* str1 = "0123456789aa";//alloc in the only read data area
    strcpy(str, str1); //array index overflow
printf("str1=%s,len=%d,sizeof = %d",str,strlen(str),sizeof(str));
/* strcpy(str1,str);  //because str1 alloced in the only read data area

 printf("str1=%s",str1);
*/
return 0;
}
--str1=0123456789aa,len=12,sizeof = 10------------

 

 

------------------

#include "stdio.h"
#include "string.h"
int main()
{
    char str[10], str1[10];
    int i = 0;
    for(; i <= 26; i++){ //memset(str,0,sizeof(str))
//modif  i< 10-1
            str[i] = 'a';
    }
    strcpy(str1, str);//find not string file end descripe
printf("str1=%s",str1);

return 0;
}
-------------反正没 coredump----

 

 

 

------------

#include "stdio.h"

int main()
{
char a;
char *str=&a;
strcpy(str,"hello");
printf(str);

return 0;
}
------------Segmentation fault--------

 

 

6 va_list 还记得么？

 

 

 

#include<stdarg.h>

int ripple ( int , ...);

main()
{
    int num;
    num = ripple ( 3, 5,7);
    printf( " %d" , num);
}

int ripple (int n, ...)
{
    int i , j;
    int k;
    va_list p;
    k= 0; j = 1;
    va_start( p , n);
    for (; j<n; ++j)  
    {
        i = va_arg( p , int);
        for (; i; i &=i-1 )     
            ++k;
    }
    return k;
}
---------------5----------

 

 

7 细心的人应该会， but not me。

 

 

#include "stdio.h"

void f(char**);
main()
{
char * argv[] = { "ab" ,"cd" , "ef" ,"gh", "ij" ,"kl" };
f( argv );

}

void f( char **p )
{ char* t; t= (p+= sizeof(int))[-1]; printf( "%s" , t);}

 

--------gh----------------

 

 

 

8  还记得 # ## 么

 

-----------

 

#include "stdio.h"
#include "string.h"

#define sss(k) #k
//#define sss(k) _sss(k)
main(){
int i=3; int j; j = sizeof(++i+ ++i); printf("i=%d j=%d", i ,j);
char buf[10] = {0};
strcpy(buf,sss(wyh));
//strcpy(buf,#wyh);
printf("/n%s/n", buf);
}

----------

 

 

#include <stdio.h>
#include <string.h>

#define STRCPY(a, b)    strcpy(a##_p, #b)
#define STRCPY1(a, b)   strcpy(a##_p, b##_p)

int main(void)  {
        char var1_p[20];
        char var2_p[30];

        strcpy(var1_p, "aaaa");
        strcpy(var2_p, "bbbb");

        STRCPY1(var1, var2);
        STRCPY(var2, var1);

        printf("var1 = %s/n", var1_p);
        printf("var2 = %s/n", var2_p);

        return 0;
}

 

-------------------------

 

10 老家伙~

 

#include <stdio.h>

int main()
{
    FILE * stream = NULL;
    unsigned char buf[64] = {0};
    unsigned char buf2[48] = {0};
    strcpy(buf, "Wang yanhui/n");
    fread((void *) buf2, 1, 5, stdin);
    fwrite((void *) buf, 1, 13, stdout);
    printf("Input = %s, Its Over!/n", buf2);
    return 0;
}

 

 

11  bit的知识

 

 

------------

#include <iostream.h>
#include <string.h>
#include <malloc.h>
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
typedef struct   AA
{
         int b1:5;
         int b2:6;
}AA;
int  main()
{
        AA aa;
        char cc[100];
        strcpy(cc,"0123456789abcdefghijklmnopqrstuvwxyz");
        memcpy(&aa,cc,sizeof(AA));
 printf("%d/n",cc[0]);
        cout << aa.b1 <<endl;
        cout << aa.b2 <<endl;
 return 0;
}

 

 

 

48
-16
9

------------

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