实验3

实验任务1：

include <stdio.h>

char score_to_grade(int score);

int main() {
int score;
char grade;

while(scanf("%d", &score) != EOF) {
    grade = score_to_grade(score);
    printf("分数: %d, 等级: %c\n\n",score,grade);
}

return 0;

}

char score_to_grade(int score) {
char ans;

switch(score/10) {
case 10:
case 9:ans = 'A'; break;
case 8:ans = 'B'; break;
case 7:ans = 'C'; break;
case 6:ans = 'D'; break;
default:ans = 'E';
}

return ans;}

1：判断学生成绩的等级；

2：int类型char 类型

3：有问题，在switch语句中没有break的情况下，如果某个case的条件满足，程序会执行case以及之后的所有case语句。
实验任务2：

include <stdio.h>

int sum_digits(int n);

int main() {
int n;
int ans;

while(printf("Enter n: "), scanf("%d", &n) != EOF) {
    ans = sum_digits(n);
    printf("n = %d, ans = %d\n\n", n, ans);
}

return 0;

}

int sum_digits(int n) {
int ans = 0;

while(n != 0) {
    ans += n % 10;
    n /= 10;
}

return ans;

}
1：返回每一位的数字相加的和；

2可以

第一种是先剥离出每一位进行相加，第二种是递归法不断相加

实验任务3：

include <stdio.h>

int power(int x, int n);

int main() {
int x, n;
int ans;

while(printf("Enter x and n: "), scanf("%d%d", &x, &n) != EOF) {
    ans = power(x, n);
    printf("n = %d, ans = %d\n\n", n, ans);
}

return 0;

}

int power(int x, int n) {
int t;

if(n == 0)
    return 1;
else if(n % 2)
    return x * power(x, n-1);
else {
    t = power(x, n/2);
    return t*t;
}

}

1功能是算出x的n次方

2：是，f(n)=f(n\2)*f(n\2\2);

实验任务4：

include<stdio.h>

include<math.h>

int is_prime(int x)
{
int i, k;
k = sqrt(x);
for(i=2;i<=k;i++)
if(x%i==0)
return 0;
if(i>k)
return 1;
}
int main(){
printf("100以内的孪生素数：\n");

int n=100;
int m=0;
int j;
for(j=2;j<=n;j++){
if(is_prime(j)&&is_prime(j+2)){
m++;
printf("%d %d\n",j,j+2);
    }
}
printf("100以内的孪生素数共有%d个\n",m);
return 0;

}
实验任务5：

include<stdio.h>

include<stdlib.h>

void hanoi(unsigned int n, char from,char temp, char
to);
void moveplate(unsigned int n ,char from, char
to);
int total=0
;
int
main()
{
unsigned
int
n;
while (scanf("%u",&n)!=
EOF){
total
= 0
;
hanoi(n,
'A', 'B', 'C'
);
printf(
"一共移动%d次"
,total);
}

return 0
;
}

void hanoi(unsigned int n, char from,char temp, char
to)
{
if(n==1
)
{
moveplate(n,
from
, to);
total
++
;
}
else
{
hanoi(n
-1, from
, to, temp);
moveplate(n,
from
, to);
hanoi(n
-1,temp, from
,to);
total
++
;
}
}
void moveplate(unsigned int n,char from, char
to)
{

printf(

"%u:%c-->%c\n",n, from
, to);
}
实验任务6：

include <stdio.h>

int func(int n, int m);

int main(){
int n, m;
int ans;

while(scanf("%d%d", &n, &m) !=EOF){
    ans = func(n, m);
    printf("n = %d, m = %d, ans = %d\n\n", n, m, ans);
}

return 0;

}
func(int n, int m)
{
int i, j;
int p=1, q=1;
for(i=n-m+1;i<=n;i++){
p=i;}
for(j=1;j<=m;j++){
q=j;}
return p/q;
}

实验任务7：

include <stdio.h>

include <stdlib.h>

void print_charman(int n);

int main() {
int n;

printf("Enter n: ");
scanf("%d", &n);
    print_charman(n); 
return 0;

}

void print_charman(int n){
int i,j,k;
for(i=n;i>0;i--){
for(k=1;k<=n-i;k++){
printf(" \t");
}
j=2*i-1;
for(j;j>0;j--){
printf(" O \t");
}
printf("\n");

    for(k=1;k<=n-i;k++){
        printf("   \t");
    }
        j=2*i-1;
        for(j;j>0;j--){
            printf("<H>\t");
        }
        printf("\n");
    for(k=1;k<=n-i;k++){
        printf("   \t");
    }
        j=2*i-1;
        for(j;j>0;j--){
            printf("I I\t");
        }printf("\n");
}

}