第五章

例子5.1

int main()
{
int i=1,sum=0;
while(i<=100)
{
sum=sum+i;
i++;
}
printf("sum=%d\n",sum);
return 0;
}

5.2

int main()
{
int i=1,sum=0;
do
{
sum=sum+i;
i++;
}while(i<=100);
printf("sum=%d\n",sum);
return 0;
}

5.3

int main()
{
int i,sum=0;
printf("please enter i,i=?");
scanf("%d",&i);
while(i<=100)
{
sum=sum+i;
i++;
}
printf("sum=%d\n",sum);
return 0;
}

int main()
{
int i,sum=0;
printf("please enter i,i=?");
scanf("%d",&i);
do
{
sum=sum+i;
i++;
}while(i<=100);
printf("sum=%d\n",sum);
return 0;
}

5.4

#define SUM 100000
int main()
{float amount,aver,total;
int i;
for(i=1,total=0;i<=1000;i++)
{
printf("please enter amount :");
scanf("%f",&amount);
total=total+amount;
if(total>=SUM)break;
}
aver=total/i;
printf("num=%d\naver=%10.2f\n",i,aver);
return 0;
}

5.5

int main()
{
int n;
for(n=100;n<=200;n++)
{
if(n%3==0)
continue;
printf("%d",n);
}
printf("\n");
return 0;
}

5.6

int main()
{
int i,j,n=0;
for(i=1;i<=4;i++)
for(j=1;j<=5;j++,n++)
{if(n%5==0)printf("\n");
printf("%d\t",i*j);
}
printf("\n");
return 0;
}

5.7

#include<math.h>
int main()
{
int sign=1;
double pi=0.0,n=1.0,tern=1.0;
while(fabs(term)>=1e-6)
{
pi=pi+term;
n=n+2;
sign=-sign;
term=sign/n;
}
pi=pi*4;
printf(pi=%10.8f\n",pi);
return 0;
}

5.8

int main()
{
int f1=1,f2=1,f3;
int i;
printf("%12d\n%12d\n",f1,f2);
for(i=1;i<=38;i++)
{
f3=f1+f2;
printf("%12d\n",f3);
f1=f2;
f2=f3;
}
return 0;
}

5.9

int main()
{
int i,n;
printf("please enter a integer number,n=?"); 
scanf("%d",&n);
for(i=2;i<n;i++)
if(n%i==0)break;
if(i<n)printf("%d is not a prime number.\n",n);
else printf("%d is a prime number.\n",n);
return 0;
}

5.10

#include<math.h>
int main()
{
int n,k,i,m=0;
for(n=101;n<=200;n=n+2)
{
k=sqrt(n);
for(i=2;i<=k;i++)
if(n%i==0)break;
if(i>=k+1)
{printf("%d",n);
m=m+1；
}
if(m%10==0)printf("\n");
}
printf("\n");
return 0;
}

5.11

int main()
{
char c;
c=getchar();
while(c!='\n')
{if((c>='a'&&c<='z')||(c>='A'&&c<='Z'))
{if(c>='W'&&c<='z'||c>='W'&&c<='z')c=c-22;
else c=c+4;
}
printf("%c",c);
c=getchar（）;
}
printf("\n");
return 0;
}