五、編寫程序(24分)
1.main()
{ float x,y;
char operator;
scanf(“%f,%c,%f”,&x,&operator,&y)
switch(operator)
{ case `+`:printf(“\n%.2f+%.2f”,x,y,x+y);break;
case `-`:printf(“\n%.2f-%.2f”,x,y,x-y);break;
case `*`:printf(“\n%.2f-%.2f”,x,y,x*y);break;
case `/`:printf(“\n%.2f-%.2f”,x,y,x/y);break;
case `/`: if(y==0)
{printf(“error!”);break;}
printf(“\n%.2f-%.2f”,x,y,x/y);break;
default:printf(“operator is invalid”);}}
2. #include “math.h”
main()
{ int m,k,i,n;
for(m=3;m《=100;m+=2)
{ k=sqrt(m);
for(i=2;i《=k;i++)
if(m%i==0) break;
if(i》=k+1)
{printf(“%d”,m);
n++;}
}}
3. #include “stdio.h”
#define ROW 3
#define COL 4
main()
{int i,j,a[ROW][COL], a[ROW][COL];
for(i=0;i《=ROW;i++)
for(j=0;j《=COL;j++)
scanf(“%d”,&a[i][j]);
for(i=0;i《=ROW;i++)
for(j=0;j《=COL;j++)
b[j][i]=a[i][j];
for(i=0;i《=ROW;i++)
for(j=0;j《=COL;j++)
printf(“%5d”,b[i][j]);}}