{ int a,b,c,d;
scanf("%d",&a);
for(b=3;b<=a/2;b+=2)
{ for(c=2;c<=sqrt(b);c++)
if(b%c==0) break;
if(c>sqrt(b))
d=a-b;
else
break;
for(c=2;c<=sqrt(d);c++)
if(d%c==0) break;
if(c>sqrt(d))
printf("%d=%d+%d\n",a,b,d);
}
}
==============================================================
【程序85】
題目：判斷一個素數能被幾個9整除
1.程序分析：
2.程序源代碼：
main()
{ long int m9=9,sum=9;
int zi,n1=1,c9=1;
scanf("%d",&zi);
while(n1!=0)
{ if(!(sum%zi))
n1=0;
else
{m9=m9*10;
sum=sum+m9;
c9++;
}
}
printf("%ld,can be divided by %d \"9\"",sum,c9);
}
==============================================================
【程序86】
題目：兩個字符串連接程序
1.程序分析：
2.程序源代碼：
#include "stdio.h"
main()
{char a[]="acegikm";
char b[]="bdfhjlnpq";
char c[80],*p;
int i=0,j=0,k=0;
while(a[i]!='\0'&&b[j]!='\0')
{if (a[i]<B[J])
{ c[k]=a[i];i++;}
else
c[k]=b[j++];
k++;
}
c[k]='\0';
if(a[i]=='\0')
p=b+j;
else
p=a+i;
strcat(c,p);
puts(c);
}
==============================================================
【程序87】
題目：回答結果（結構體變量傳遞）
1.程序分析：　　　　　
2.程序源代碼：
#include "stdio.h"
struct student
{ int x;
char c;
} a;
main()
{a.x=3;
a.c='a';
f(a);
printf("%d,%c",a.x,a.c);
}
f(struct student b)
{
b.x=20;
b.c='y';
}
==============================================================
【程序88】
題目：讀取7個數（1—50）的整數值，每讀取一個值，程序打印出該值個數的＊。
1.程序分析：
2.程序源代碼：
main()
{int i,a,n=1;
while(n<=7)
{ do {
　　　scanf("%d",&a);
　　　}while(a<1||a>50);
for(i=1;i<=a;i++)
　printf("*");
printf("\n");
n++;}
getch();
}
==============================================================
【程序89】
題目：某個公司采用公用電話傳遞數據，數據是四位的整數，在傳遞過程中是加密的，加密規則如下：
　　　每位數字都加上5,然后用和除以10的余數代替該數字，再將第一位和第四位交換，第二位和第三位交換。
1.程序分析：
2.程序源代碼：
main()
{int a,i,aa[4],t;
scanf("%d",&a);
aa[0]=a%10;
aa[1]=a%100/10;
aa[2]=a%1000/100;
aa[3]=a/1000;
for(i=0;i<=3;i++)
　{aa[i]+=5;
　aa[i]%=10;
　}
for(i=0;i<=3/2;i++)
　{t=aa[i];
　aa[i]=aa[3-i];
　aa[3-i]=t;
　}
for(i=3;i>=0;i--)
printf("%d",aa[i]);
}
==============================================================
【程序90】
題目：專升本一題，讀結果。
1.程序分析：
2.程序源代碼：
#include "stdio.h"
#define M 5
main()
{int a[M]={1,2,3,4,5};
int i,j,t;
i=0;j=M-1;
while(i<J)
{t=*(a+i);
*(a+i)=*(a+j);
*(a+j)=t;
i++;j--;
}
for(i=0;i<M;I++)
printf("%d",*(a+i));
}

【程序91】
題目：時間函數舉例1
1.程序分析：
2.程序源代碼：
#include "stdio.h"
#include "time.h"
void main()
{ time_t lt; /*define a longint time varible*/
lt=time(NULL);/*system time and date*/
printf(ctime(<)); /*english format output*/
printf(asctime(localtime(<)));/*tranfer to tm*/
printf(asctime(gmtime(<))); /*tranfer to Greenwich time*/
}
==============================================================
【程序92】
題目：時間函數舉例2
1.程序分析：　　　　　　　　　　　
2.程序源代碼：
/*calculate time*/
#include "time.h"
#include "stdio.h"
main()
{ time_t start,end;
int i;
start=time(NULL);
for(i=0;i<3000;i++)
{ printf("\1\1\1\1\1\1\1\1\1\1\n");}
end=time(NULL);
printf("\1: The different is %6.3f\n",difftime(end,start));
}
==============================================================
【程序93】
題目：時間函數舉例3
1.程序分析：
2.程序源代碼：
/*calculate time*/
#include "time.h"
#include "stdio.h"
main()
{ clock_t start,end;
int i;
double var;
start=clock();
for(i=0;i<10000;i++)
{ printf("\1\1\1\1\1\1\1\1\1\1\n");}
end=clock();
printf("\1: The different is %6.3f\n",(double)(end-start));
}
==============================================================
【程序94】
題目：時間函數舉例4,一個猜數游戲，判斷一個人反應快慢。（版主初學時編的）
1.程序分析：
2.程序源代碼：
#include "time.h"
#include "stdlib.h"
#include "stdio.h"
main()
{char c;
clock_t start,end;
time_t a,b;
double var;
int i,guess;
srand(time(NULL));
printf("do you want to play it.('y' or 'n') \n");
loop:
while((c=getchar())=='y')
{
i=rand()%100;
printf("\nplease input number you guess:\n");
start=clock();
a=time(NULL);
scanf("%d",&guess);
while(guess!=i)
{if(guess>i)
{printf("please input a little smaller.\n");
scanf("%d",&guess);}
else
{printf("please input a little bigger.\n");
scanf("%d",&guess);}
}
end=clock();
b=time(NULL);
printf("\1: It took you %6.3f seconds\n",var=(double)(end-start)/18.2);
printf("\1: it took you %6.3f seconds\n\n",difftime(b,a));
if(var<15)
printf("\1\1 You are very clever! \1\1\n\n");
else if(var<25)
printf("\1\1 you are normal! \1\1\n\n");
else
printf("\1\1 you are stupid! \1\1\n\n");
printf("\1\1 Congradulations \1\1\n\n");
printf("The number you guess is %d",i);
}
printf("\ndo you want to try it again?(\"yy\".or.\"n\")\n");
if((c=getch())=='y')
goto loop;
}
==============================================================
【程序95】
題目：家庭財務管理小程序
1.程序分析：
2.程序源代碼：
/*money management system*/
#include "stdio.h"
#include "dos.h"
main()
{
FILE *fp;
struct date d;
float sum,chm=0.0;
int len,i,j=0;
int c;
char ch[4]="",ch1[16]="",chtime[12]="",chshop[16],chmoney[8];
pp: clrscr();
sum=0.0;
gotoxy(1,1);printf("|---------------------------------------------------------------------------|");
gotoxy(1,2);printf("| money management system(C1.0) 2000.03 |");
gotoxy(1,3);printf("|---------------------------------------------------------------------------|");
gotoxy(1,4);printf("| -- money records -- | -- today cost list -- |");
gotoxy(1,5);printf("| ------------------------ |-------------------------------------|");
gotoxy(1,6);printf("| date: -------------- | |");
gotoxy(1,7);printf("| | | | |");
gotoxy(1,8);printf("| -------------- | |");
gotoxy(1,9);printf("| thgs: ------------------ | |");
gotoxy(1,10);printf("| | | | |");
gotoxy(1,11);printf("| ------------------ | |");
gotoxy(1,12);printf("| cost: ---------- | |");
gotoxy(1,13);printf("| | | | |");
gotoxy(1,14);printf("| ---------- | |");
gotoxy(1,15);printf("| | |");
gotoxy(1,16);printf("| | |");
gotoxy(1,17);printf("| | |");
gotoxy(1,18);printf("| | |");
gotoxy(1,19);printf("| | |");
gotoxy(1,20);printf("| | |");
gotoxy(1,21);printf("| | |");
gotoxy(1,22);printf("| | |");
gotoxy(1,23);printf("|---------------------------------------------------------------------------|");
i=0;
getdate(&d);
sprintf(chtime,"%4d.%02d.%02d",d.da_year,d.da_mon,d.da_day);
for(;;)
{
gotoxy(3,24);printf(" Tab __browse cost list Esc __quit");
gotoxy(13,10);printf(" ");
gotoxy(13,13);printf(" ");
gotoxy(13,7);printf("%s",chtime);
j=18;
ch[0]=getch();
if(ch[0]==27)
break;
strcpy(chshop,"");
strcpy(chmoney,"");
if(ch[0]==9)
{
mm:i=0;
fp=fopen("home.dat","r+");
gotoxy(3,24);printf(" ");
gotoxy(6,4);printf(" list records ");
gotoxy(1,5);printf("|-------------------------------------|");
gotoxy(41,4);printf(" ");
gotoxy(41,5);printf(" |");
while(fscanf(fp,"%10s%14s%f\n",chtime,chshop,&chm)!=EOF)
{ if(i==36)
{ getch();
i=0;}
if ((i%36)<17)
{ gotoxy(4,6+i);
printf(" ");
gotoxy(4,6+i);}
else
if((i%36)>16)
{ gotoxy(41,4+i-17);
printf(" ");
gotoxy(42,4+i-17);}
i++;
sum=sum+chm;
printf("%10s %-14s %6.1f\n",chtime,chshop,chm);}
gotoxy(1,23);printf("|---------------------------------------------------------------------------|");
gotoxy(1,24);printf("| |");
gotoxy(1,25);printf("|---------------------------------------------------------------------------|");
gotoxy(10,24);printf("total is %8.1f$",sum);
fclose(fp);
gotoxy(49,24);printf("press any key to.....");getch();goto pp;
}
else
{
while(ch[0]!='\r')
{ if(j<10)
{ strncat(chtime,ch,1);
j++;}
if(ch[0]==8)
{
len=strlen(chtime)-1;
if(j>15)
{ len=len+1; j=11;}
strcpy(ch1,"");
j=j-2;
strncat(ch1,chtime,len);
strcpy(chtime,"");
strncat(chtime,ch1,len-1);
gotoxy(13,7);printf(" ");}
gotoxy(13,7);printf("%s",chtime);ch[0]=getch();
if(ch[0]==9)
goto mm;
if(ch[0]==27)
exit(1);
}
gotoxy(3,24);printf(" ");
gotoxy(13,10);
j=0;
ch[0]=getch();
while(ch[0]!='\r')
{ if (j<14)
{ strncat(chshop,ch,1);
j++;}
if(ch[0]==8)
{ len=strlen(chshop)-1;
strcpy(ch1,"");
j=j-2;
strncat(ch1,chshop,len);
strcpy(chshop,"");
strncat(chshop,ch1,len-1);
gotoxy(13,10);printf(" ");}
gotoxy(13,10);printf("%s",chshop);ch[0]=getch();}
gotoxy(13,13);
j=0;
ch[0]=getch();
while(ch[0]!='\r')
{ if (j<6)
{ strncat(chmoney,ch,1);
j++;}
if(ch[0]==8)
{ len=strlen(chmoney)-1;
strcpy(ch1,"");
j=j-2;
strncat(ch1,chmoney,len);
strcpy(chmoney,"");
strncat(chmoney,ch1,len-1);
gotoxy(13,13);printf(" ");}
gotoxy(13,13);printf("%s",chmoney);ch[0]=getch();}
if((strlen(chshop)==0)||(strlen(chmoney)==0))
continue;
if((fp=fopen("home.dat","a+"))!=NULL);
fprintf(fp,"%10s%14s%6s",chtime,chshop,chmoney);
fputc('\n',fp);
fclose(fp);
i++;
gotoxy(41,5+i);
printf("%10s %-14s %-6s",chtime,chshop,chmoney);
}}} 
==============================================================
【程序96】
題目：計算字符串中子串出現的次數
1.程序分析：
2.程序源代碼：
#include "string.h"
#include "stdio.h"
main()
{ char str1[20],str2[20],*p1,*p2;
int sum=0;
printf("please input two strings\n");
scanf("%s%s",str1,str2);
p1=str1;p2=str2;
while(*p1!='\0')
{
if(*p1==*p2)
{while(*p1==*p2&&*p2!='\0')
{p1++;
p2++;}
}
else
p1++;
if(*p2=='\0')
sum++;
p2=str2;
}
printf("%d",sum);
getch();} 
==============================================================
【程序97】
題目：從鍵盤輸入一些字符，逐個把它們送到磁盤上去，直到輸入一個#為止。
1.程序分析：　　　　　
2.程序源代碼：
#include "stdio.h"
main()
{ FILE *fp;
char ch,filename[10];
scanf("%s",filename);
if((fp=fopen(filename,"w"))==NULL)
{printf("cannot open file\n");
exit(0);}
ch=getchar();
ch=getchar();
while(ch!='#')
{fputc(ch,fp);putchar(ch);
ch=getchar();
}
fclose(fp);
}
==============================================================
【程序98】
題目：從鍵盤輸入一個字符串，將小寫字母全部轉換成大寫字母，然后輸出到一個磁盤文件“test”中保存。
　　　輸入的字符串以！結束。 
1.程序分析：
2.程序源代碼：
#include "stdio.h"
main()
{FILE *fp;
char str[100],filename[10];
int i=0;
if((fp=fopen("test","w"))==NULL)
{ printf("cannot open the file\n");
exit(0);}
printf("please input a string:\n");
gets(str);
while(str[i]!='!')
{ if(str[i]>='a'&&str[i]<='z')
str[i]=str[i]-32;
fputc(str[i],fp);
i++;}
fclose(fp);
fp=fopen("test","r");
fgets(str,strlen(str)+1,fp);
printf("%s\n",str);
fclose(fp);
}
==============================================================
【程序99】
題目：有兩個磁盤文件A和B,各存放一行字母，要求把這兩個文件中的信息合并（按字母順序排列）， 
　　　輸出到一個新文件C中。
1.程序分析：
2.程序源代碼：
#include "stdio.h"
main()
{ FILE *fp;
int i,j,n,ni;
char c[160],t,ch;
if((fp=fopen("A","r"))==NULL)
{printf("file A cannot be opened\n");
exit(0);}
printf("\n A contents are :\n");
for(i=0;(ch=fgetc(fp))!=EOF;i++)
{c[i]=ch;
putchar(c[i]);
}
fclose(fp);
ni=i;
if((fp=fopen("B","r"))==NULL)
{printf("file B cannot be opened\n");
exit(0);}
printf("\n B contents are :\n");
for(i=0;(ch=fgetc(fp))!=EOF;i++)
{c[i]=ch;
putchar(c[i]);
}
fclose(fp);
n=i;
for(i=0;i<n;i++)
for(j=i+1;j<n;j++)
if(c[i]>c[j])
{t=c[i];c[i]=c[j];c[j]=t;}
printf("\n C file is:\n");
fp=fopen("C","w");
for(i=0;i<n;i++)
{ putc(c[i],fp);
putchar(c[i]);
}
fclose(fp);
}
==============================================================
【程序100】
題目：有五個學生，每