第二章练习参考答案
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第二章练习参考答案
P55-4
方法1：
#include
main()
{
int y;
printf("Please enter a year:");
scanf("%d",&y);
if(y%400==0)
printf("It is a leap year.\n");
else
if(y%4==0 && y%100!=0)
printf("It is a leap year.\n");
else
printf("It is not a leap year.\n");
}
方法2：
#include
main()
{
int y;
printf ("Please enter a year:");
scanf ( "%d",&y);
if ( y%4==0 && y%100!=0 || y%400==0 )
printf("It is a leap year.\n");
else
printf("It is not a leap year.\n");
}
P55-5
方法1：
#include
main()
{
int year,month;
printf("Please enter a year and a month:");
scanf("%d%d",&year,&month);
switch(month){
case 4: case 6: case 9: case 11:
printf("It has 30 days.\n");
break;
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
printf("It has 31 days.\n");
break;
case 2:
if(year%400==0)
printf("It has 29 days.\n");
else
if(year%4==0 && year%100!=0)
printf("It has 29 days.\n");
else
printf("It has 28 days.\n");
}
}
方法2：
#include
main()
{
int year, month, day;
printf("Please enter a year and a month:");
scanf("%d%d", &year, &month);
switch(month) {
case 4: case 6: case 9: case 11:
day = 30;
break;
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
day = 31;
break;
case 2:
if(year%400==0 || (year%4==0 && year%100!=0))
day = 29;
else
day = 28;
}
printf("It has %d days.\n", day);
}
P55-6
#include
#define N 100
main( )
{
int x, i, sum=0, n=0;
printf("\nEnter 100 integer number :\n");
for(i=1; i<=N; i++) {
scanf("%d", &x);
if ( x%2==0 ) {
sum = sum + x;
n++;
}
}
printf("%.2f\n", 1.0*sum/n);
}
P55-7
#include
main( )
{
int x,i;
printf("\nEnter an integer number (>0) :"); scanf("%d", &x);
for ( i = 1; i<=x; i++)
if ( x%i==0 )
printf("%4d", i);
}
P55-8
#include
main()
{
int x, i;
printf("Please Enter a integer: ");
scanf("%d", &x);
for(i=2; i if (x%i==0) break; if(i printf("%d is not prime.\n",x); else printf("%d is prime.\n",x); } P55-9 方法1： #include main() { int x = 2, i, num = 0; while (x < 100) { i = 2 while (i <= x) {