实验四

task1

`#include <stdio.h>

define N 4

define M 2

void test1() {
int x[N] = {1, 9, 8, 4};
int i;

printf("sizeof(x) = %d\n", sizeof(x));

for (i = 0; i < N; ++i)
printf("%p: %d\n", &x[i], x[i]);

printf("x = %p\n", x);
}

void test2() {
int x[M][N] = {{1, 9, 8, 4}, {2, 0, 4, 9}};
int i, j;

printf("sizeof(x) = %d\n", sizeof(x));

for (i = 0; i < M; ++i)
for (j = 0; j < N; ++j)
printf("%p: %d\n", &x[i][j], x[i][j]);
printf("\n");
printf("x = %p\n", x);
printf("x[0] = %p\n", x[0]);
printf("x[1] = %p\n", x[1]);
printf("\n");
}

int main() {
printf("测试1: int型一维数组\n");
test1();

printf("\n测试2: int型二维数组\n");
test2();

return 0;
}`
运行结果截图

task2

`#include <stdio.h>

define N 100

// 函数声明
void input(int x[], int n);
double compute(int x[], int n);

int main() {
int x[N];
int n, i;
double ans;

while(printf("Enter n: "), scanf("%d", &n) != EOF) {
input(x, n); // 函数调用
ans = compute(x, n); // 函数调用
printf("ans = %.2f\n\n", ans);
}

return 0;
}

// 函数定义
void input(int x[], int n) {
int i;

for(i = 0; i < n; ++i)
scanf("%d", &x[i]);
}

// 函数定义
double compute(int x[], int n) {
int i, high, low;
double ans;

high = low = x[0];
ans = 0;

for(i = 0; i < n; ++i) {
ans += x[i];

if(x[i] > high)
high = x[i];
else if(x[i] < low)
low = x[i];
}

ans = (ans - high - low)/(n-2);

return ans;
}`
运行结果截图

问题1：int x[ ] ; input(x, n)
问题2：把输入的n个整数依次存入数组x中；
计算数组x中元素去掉一个最大值和一个最小值后的平均值

task3

`#include <stdio.h>

define N 100

void output(int x[][N], int n);
void init(int x[][N], int n, int value);

int main() {
int x[N][N];
int n, value;

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

return 0;
}

void output(int x[][N], int n) {
int i, j;

for(i = 0; i < n; ++i) {
for(j = 0; j < n; ++j)
printf("%d ", x[i][j]);
printf("\n");
}
}

void init(int x[][N], int n, int value) {
int i, j;

for(i = 0; i < n; ++i)
for(j = 0; j < n; ++j)
x[i][j] = value;
}`
运行结果截图

问题1：形参：int x[ ][N]
实参：x
问题2：不能省略第二维
问题3：init函数：给二维数组赋值
output函数：输出二维数组

task4

`#include <stdio.h>

define N 100

void input(int x[], int n);
double median(int x[], int n);

int main() {
int x[N];
int n;
double ans;
while (printf("Enter n: "), scanf("%d", &n) != EOF) {
input(x, n);
ans = median(x, n);
printf("ans = %g\n\n", ans);
}
return 0;
}

void input(int x[], int n) {
int i;
for (i = 0; i < n; ++i) {
scanf("%d", &x[i]);
}
}

double median(int x[], int n) {
int i, j, temp;
for (i = 0; i < n - 1; ++i) {
for (j = 0; j < n - 1 - i; ++j) {
if (x[j] > x[j + 1]) {
temp = x[j];
x[j] = x[j + 1];
x[j + 1] = temp;
}
}
}

if (n % 2 == 1) {
return (double)x[n / 2];
} else {
return (double)(x[n / 2 - 1] + x[n / 2]) / 2.0;
}
}`
运行结果截图

task5

`#include <stdio.h>

define N 100

void input(int x[][N], int n);
void output(int x[][N], int n);
void rotate_to_right(int x[][N], int n);

int main() {
int x[N][N];
int n;
printf("Enter n: ");
scanf("%d", &n);
input(x, n);
printf("原始矩阵:\n");
output(x, n);

rotate_to_right(x, n);

printf("变换后矩阵:\n");
output(x, n);
return 0;
}

void input(int x[][N], int n) {
int i, j;
for (i = 0; i < n; ++i) {
for (j = 0; j < n; ++j)
scanf("%d", &x[i][j]);
}
}

void output(int x[][N], int n) {
int i, j;
for (i = 0; i < n; ++i) {
for (j = 0; j < n; ++j)
printf("%4d", x[i][j]);
printf("\n");
}
}

void rotate_to_right(int x[][N], int n) {
int i, j, last;
for (i = 0; i < n; ++i) {
last = x[i][n - 1];
for (j = n - 1; j > 0; --j) {
x[i][j] = x[i][j - 1];
}
x[i][0] = last;
}
}`
运行结果截图

task6

`#include <stdio.h>

define N 100

void dec_to_n(int x, int n); // 函数声明

int main() {
int x;

while(printf("输入十进制整数: "), scanf("%d", &x) != EOF) {
dec_to_n(x, 2);
dec_to_n(x, 8);
dec_to_n(x, 16);

printf("\n");
}

return 0;
}
void dec_to_n(int x, int n){
int r[N], i=0;

if (x==0){
printf("0\n");
return;
}

while (x>0){
r[i++] = x % n;
x /= n;
}

for(i--; i>= 0; i--){
printf("%c", r[i]< 10 ?r[i] +'0' : r[i]-10 +'A');
}
printf("\n");
}`
运行结果截图

task7

`#include <stdio.h>

define N 100

void input(int x[][N], int n);
void output(int x[][N], int n);
int is_magic(int x[][N], int n);

int main() {
int x[N][N];
int n;
while (printf("输入n: "), scanf("%d", &n) != EOF) {
printf("输入方阵:\n");
input(x, n);
printf("输出方阵:\n");
output(x, n);
if (is_magic(x, n))
printf("是魔方矩阵\n\n");
else
printf("不是魔方矩阵\n\n");
}
return 0;
}

void input(int x[][N], int n) {
int i, j;
for (i = 0; i < n; ++i) {
for (j = 0; j < n; ++j)
scanf("%d", &x[i][j]);
}
}

void output(int x[][N], int n) {
int i, j;
for (i = 0; i < n; ++i) {
for (j = 0; j < n; ++j)
printf("%4d", x[i][j]);
printf("\n");
}
}

int is_magic(int x[][N], int n) {
int i, j;
int target;
int sum;
int used[N * N + 1] = {0};

if (n % 2 == 0 || n <= 0)
return 0;

target = n * (n * n + 1) / 2;

for (i = 0; i < n; ++i) {
for (j = 0; j < n; ++j) {
int val = x[i][j];
if (val < 1 || val > n * n || used[val])
return 0;
used[val] = 1;
}
}

for (i = 0; i < n; ++i) {
sum = 0;
for (j = 0; j < n; ++j)
sum += x[i][j];
if (sum != target)
return 0;
}

for (j = 0; j < n; ++j) {
sum = 0;
for (i = 0; i < n; ++i)
sum += x[i][j];
if (sum != target)
return 0;
}

sum = 0;
for (i = 0; i < n; ++i)
sum += x[i][i];
if (sum != target)
return 0;

sum = 0;
for (i = 0; i < n; ++i)
sum += x[i][n - 1 - i];
if (sum != target)
return 0;

return 1;
}`
运行结果截图