090902c语言日记（指针，数组）

#include<stdio.h>int maxnum(int ar[],int n);int main(void){ int mar[5]={1,2,3,8,5}; printf(" max is %d/n",maxnum(mar,5)); getch(); return 0;}int maxnum(int ar[],int n){ int i; int max; for(i=1;i<n;i++) max=ar[i]>ar[i-1]?i:(i-1); return max;} #include <stdio.h>#define MONTHS 12 #define YRS 5 int main(void){ const float rain[YRS][MONTHS] = { {10.2, 8.1, 6.8, 4.2, 2.1, 1.8, 0.2, 0.3, 1.1, 2.3, 6.1, 7.4}, {9.2, 9.8, 4.4, 3.3, 2.2, 0.8, 0.4, 0.0, 0.6, 1.7, 4.3, 5.2}, {6.6, 5.5, 3.8, 2.8, 1.6, 0.2, 0.0, 0.0, 0.0, 1.3, 2.6, 4.2}, {4.3, 4.3, 4.3, 3.0, 2.0, 1.0, 0.2, 0.2, 0.4, 2.4, 3.5, 6.6}, {8.5, 8.2, 1.2, 1.6, 2.4, 0.0, 5.2, 0.9, 0.3, 0.9, 1.4, 7.2} }; int year, month; float subtot, total; printf(" YEAR RAINFALL (inches)/n"); for (year = 0, total = 0; year < YRS; year++) { for (month = 0, subtot = 0; month < MONTHS; month++) subtot += *(*(rain + year) + month); printf("%5d %15.1f/n", 1990 + year, subtot); total += subtot; } printf("/nThe yearly average is %.1f inches./n/n", total/YRS); printf("MONTHLY AVERAGES:/n/n"); printf(" Jan Feb Mar Apr May Jun Jul Aug Sep Oct "); printf(" Nov Dec/n"); for (month = 0; month < MONTHS; month++) { for (year = 0, subtot =0; year < YRS; year++) subtot += *(*(rain + year) + month); printf("%4.1f ", subtot/YRS); } printf("/n"); getch(); return 0;} #include<stdio.h>#define SIZE 4int main(void){ short dates [SIZE]; short *pti; short index; double bills[SIZE]; double * ptf; pti=dates; ptf=bills; printf("%23s %10s/n","short","double"); for(index=0;index<SIZE;index++) printf("pointers + %d: %10p %10p/n", index,pti+index,ptf+index); getch(); return 0;}

#include<stdio.h>#define SIZE 10 int sum(int *,int *);int main(void){ int marbles[SIZE]={20,12,23,23,45,12,88,5,55,41}; long answer; answer=sum(marbles,marbles+SIZE);//注意这里 printf("The total is %ld./n",answer); getch(); return 0;}int sum(int *start,int *end){ int total=0; while(start<end) { total+=*start; start++;//把指针向前推进到下一个元素 ，可以等于total+=*start++；*和++具有相同的优先级，但是却是从右到左结合 } return total;}

//指针运算的优先级#include<stdio.h>int data[2]={100,200};int moredata[2]={300,400};int main(void){ int * p1,* p2,* p3; p1=p2=data; p3=moredata; printf(" *p1=%d, *p2=%d, *p3=%d./n", *p1 ,*p2 , *p3 ); printf("*p1++=%d, *++p2=%d, (*p3)++=%d/n", *p1++ , *++p2 ,(*p3)++); printf(" *p1=%d, *p2=%d, *p3=%d./n", *p1 ,*p2 , *p3 ); getch(); return 0;}

 

  *p1=100,    *p2=100,     *p3=300.
*p1++=100,   *++p2=200,   (*p3)++=300
 *p1=200,    *p2=200,     *p3=301.

//指针操作#include<stdio.h>int main(void){ int urn[5]={100,200,300,400,500}; int * ptr1,* ptr2,* ptr3; ptr1=urn; ptr2=&urn[2]; printf("pointer value, dereferenced pointer, pointer address:/n"); printf("ptr1=%p,*ptr1=%d,&ptr1=%p/n",ptr1,*ptr1,&ptr1); //指针加法 ptr3=ptr1+4; printf("/nadding an int to a pointer:/n"); printf("ptr1+4=%p,*(ptr1+3)=%d/n",ptr1+4,*(ptr1+3)); ptr1++;//递增指针 printf("/nvalues after ptr1++:/n"); printf("ptr1=%p,*ptr1=%d,&ptr1=%p /n",ptr1,*ptr1,&ptr1); ptr2--; // 递减指针 printf("/nvalues after --ptr2:/n"); printf("ptr2 = %p, *ptr2 = %d, &ptr2 = %p/n",ptr2, *ptr2, &ptr2); --ptr1; ++ptr2;//恢复原值 printf("/nPointers reset to original values:/n"); printf("ptr1 = %p, ptr2 = %p/n", ptr1, ptr2); printf("/nsubtracting one pointer from another:/n"); printf("ptr2=%p,ptr1=%p,ptr2-ptr1=%d/n",ptr2,ptr1,ptr2-ptr1);//一个指针减去另一个指针 printf("/nsubtracting an int from a pointer:/n"); printf("ptr3 = %p, ptr3 - 2 = %p/n",ptr3, ptr3 - 2);//指针减去整数 printf("ptr3-2=%p,*ptr3=%d/n",ptr3-2,*(ptr3-2)); getch(); return 0;}pointer value, dereferenced pointer, pointer address:ptr1=0022FF50,*ptr1=100,&ptr1=0022FF4Cadding an int to a pointer:ptr1+4=0022FF60,*(ptr1+3)=400values after ptr1++:ptr1=0022FF54,*ptr1=200,&ptr1=0022FF4Cvalues after --ptr2:ptr2 = 0022FF54, *ptr2 = 200, &ptr2 = 0022FF48Pointers reset to original values:ptr1 = 0022FF50, ptr2 = 0022FF58subtracting one pointer from another:ptr2=0022FF58,ptr1=0022FF50,ptr2-ptr1=2subtracting an int from a pointer:ptr3 = 0022FF60, ptr3 - 2 = 0022FF58ptr3-2=0022FF58,*ptr3=300void add_to (double ar[],int n,double val){ int i; for(i=0;i<n;i++) ar[i]+=val;}

//处理数组的函数#include<stdio.h>#define SIZE 5void show_array(const double ar[],int n);//使用const保护数组void mult_array(double ar[],int n,double mult);int main(void){ double dip[SIZE]={20.00,17.66,8.2,15.3,22.22}; show_array(dip,SIZE); mult_array(dip,SIZE,2.5); printf("THe dip array calling mult_array():/n"); show_array(dip,SIZE); getch(); return 0;}void show_array(const double ar[],int n){ int i; for(i=0;i<n;i++) printf("%8.3f",ar[i]); putchar('/n'); }void mult_array(double ar[],int n,double mult){ int i; for(i=0;i<n;i++) ar[i]*=mult;}

#include<stdio.h>int main(void){ int zippo[4][2]={{2,4},{6,8},{1,3},{5,7}}; printf(" zippo=%p, zippo+1=%p/n", zippo, zippo+1); printf(" zippo[0]=%p, zippo[0]+1=%p/n", zippo[0], zippo[0]+1); printf(" *zippo=%p, *zippo+1=%p/n", *zippo, *zippo+1); printf("zippo[0][0]=%d/n",zippo[0][0]); printf(" *zippo[0]=%d/n",*zippo[0]); printf(" **zippo=%d/n",**zippo); printf(" zippo[2][1]=%d/n",zippo[2][1]); printf("*(*(zippo+2) +1)=%d/n",*(*(zippo+2)+1)); getch(); return 0;}

   zippo=0022FF50,    zippo+1=0022FF58
  zippo[0]=0022FF50,  zippo[0]+1=0022FF54
  *zippo=0022FF50,  *zippo+1=0022FF54
zippo[0][0]=2
  *zippo[0]=2
  **zippo=2
    zippo[2][1]=3
*(*(zippo+2) +1)=3

#include<stdio.h>int main(void){ int zippo[4][2]={{2,4},{6,8},{1,3},{5,7}}; int (*pz) [2]; pz=zippo; printf("pz=%p, pz+1=%p/n", pz, pz+1); printf("pz[0]=%p, pz[0]+1=%p/n", pz[0], pz[0]+1); printf("*pz=%p,*pz+1=%p/n", *pz , *pz+1); printf("pz[0][0]=%d/n",pz[0][0]); printf(" *pz[0]=%d/n",*pz[0]); printf(" **pz=%d/n",**pz); printf(" pz[2][1]=%d/n",pz[2][1]); printf("*(*(pz+2)+1)=%d/n",*(*(pz+2)+1)); getch(); return 0;}

//变长数组#include<stdio.h>#define ROWS 3#define COLS 4int sum2d(int rows,int cols,int ar[rows][cols]);int main(void){ int i ,j; int rs=3; int cs=10; int junk[ROWS][COLS]={ {2,4,6,8}, {3,7,5,9}, {12,10,8,6} }; int morejunk[ROWS-1][COLS+2]= { {20,30,40,50,60,70}, {5,6,7,8,9,10} }; int varr[rs][cs]; for(i=0;i<rs;i++) for(j=0;j<cs;j++) varr[i][j]=i*j+j; printf("3x5 array|N"); printf("sum of all elements =%d/n", sum2d(ROWS,COLS,junk)); printf("2x6 array/n"); printf("sum of all elements =%d/n", sum2d(ROWS-1,COLS+2,morejunk)); printf("3x10 VLA/n"); printf("sum of all elements =%d/n", sum2d(rs,cs,varr)); getch(); return 0;} int sum2d(int rows,int cols,int ar[rows][cols]){ int r; int c; int tot=0; for(r=0;r<rows;r++) for(c=0;c<cols;c++) tot+=ar[r][c]; return tot; }

//复合文字#include<stdio.h>#define COLS 4int sum2d(int ar[][COLS],int rows);int sum(int ar[],int n);int main(void){ int total1,total2,total3; int *pt1; int (*pt2) [COLS]; pt1=(int [2]) {10,20}; pt2=(int [2][COLS]) { {1,2,3,-9}, {4,5,6,-8} }; total1=sum(pt1,2); total2=sum2d(pt2,2); total3=sum((int []) {4,4,4,5,5,5},6);//注意这里 printf("total1=%d/n",total1); printf("total2=%d/n",total2); printf("total3=%d/n",total3); getch(); return 0;}int sum(int ar[],int n){ int i; int total=0; for(i=0;i<n;i++) total+=ar[i]; return total;}int sum2d(int ar[][COLS],int rows){ int r; int c; int tot=0; for(r=0;r<rows;r++) for(c=0;c<COLS;c++) tot+=ar[r][c]; return tot;}
void process(double ar[],int n);
void processvla(int n,double ar[n]);
process(trots,20);
processvla(20,trots);
void process(short ar2[30],short r);
void processvla(short r,short s,short ar2[r][s]);
process2(clops,10);
process2vla(10,30,clops);

void process(long ar3[10][15],long r);
void processvla(long r ,long s,long t,ar3[r][s][t]); 
process3(shots,5);
process3vla(5,10,15,shots);
                           
show((int [4]) {8,3,9,2},4);
show2((int [][3]) {{8,3,9},{5,4,1}},2);

#include<stdio.h>void copy1(double ar[],double ar1[],int n);void copy2(double *ar,double *ar2,int n);void showar(const double ar[],int n);int main(void){ double ar[4]={2.1,2.1,3.1,4.1}; double ar1[4]; double ar2[4]; copy1(ar, ar1,4); copy2(ar, ar2,4); showar(ar1,4); showar(ar2,4); getch(); return 0;}void copy1(double ar[],double ar1[],int n){ int i; for(i=0;i<n;i++) { ar1[i]=ar[i]; }}void copy2(double *ar,double *ar2,int n){ int i; for(i=0;i<n;i++) { *(ar2+i)=*(ar+i); }} void showar(const double ary[],int n){ int i; for(i=0;i<n;i++) printf("%8.3f",ary[i]); putchar('/n');}

#include<stdio.h>int maxnum(int ar[],int n);int main(void){ int mar[5]={1,2,3,8,5}; printf(" max is %d/n",maxnum(mar,5)); getch(); return 0;}int maxnum(int ar[],int n){ int i; int max; for(i=1;i<n;i++) max=ar[i]>ar[i-1]?ar[i]:ar[i-1]; return max;}

 

 

 

 

 

#include<stdio.h>int maxnum(int ar[],int n);int main(void){ int mar[5]={1,2,3,8,5}; printf(" max is %d/n",maxnum(mar,5)); getch(); return 0;}int maxnum(int ar[],int n){ int i; int max=ar[0]; int min=ar[0]; for(i=1;i<n;i++) if(max<ar[i]) max=ar[i]; else if(min>ar[i]) min=ar[i]; return max-min;}