练习8-1
#define diff(x,y)(x-y)
int main() {
int x;
int y;
printf("x="); scanf("%d", &x);
printf("y="); scanf("%d", &y);
printf("%d", diff(x, y));
return 0;
}
练习8-2
#define max(x,y) ((x)>(y)?x:y)
int main()
{
int a, b, c, d;
int max1, max2;
printf("输入a b c d 的值:\n");
scanf("%d", &a);
scanf("%d", &b);
scanf("%d", &c);
scanf("%d", &d);
max1 = max(max(a, b), max(c, d)); //是先求出a，b一组和c，d一组中的较大值，再比较两个较大值求最大值
printf("最大值是%d", max1);
putchar('\n');
max2 = max(max(max(a, b), c), d); //依次比较a和b的较大值，再用较大值依次比较c，d，而求出最大值
printf("最大值是%d", max2);
return 0;
}
练习8-3
#include <stdio.h>
#define swap(int,a,b) {int temp;temp = a;x = y;y = temp;}
int main()
{
int x = 5;
int y = 10;
swap(int, x, y);
printf("x = %d\ny = %d\n", x, y);
return 0;
}
练习8-4
#include <stdio.h>
#define number 6
void bsort(int n, int v[])
{
int i, j;
for (i = 0; i < n - 1; i++) {
for (j = n - 1; j > i; j--) {
if (v[j - 1] < v[j]) {
int tem = v[j];
v[j] = v[j - 1];
v[j - 1] = tem;
}
}
}
}
int main()
{
int i;
int v[number];
for (i = 0; i < number; i++) {
printf("v[%d]=", i);
scanf("%d", &v[i]);
}
putchar('\n');
bsort(number, v);
for (i = 0; i < number; i++)
{
printf("v[%d]=%d\n", i, v[i]);
}
return 0;
}
练习8-5
#include <stdio.h>
enum sex {boy, girl, Invaild};
enum season {Spring, summer, fall, winter, Invaild};
int main() {
enum sex s;
enum season se;
printf("请输入性别（男孩/女孩）：");
scanf("%d", &s);
printf("请输入季节（春/夏/秋/冬）：");
scanf("%d", &se);
if (s == boy && (se == spring || se == summer)) {
printf("男孩喜欢%s\n", (se == spring) ? "春天" : "夏天");
}
else if (s == girl && (se == spring || se == summer)) {
printf("女孩喜欢%s\n", (se == spring) ? "春天" : "夏天");
}
else if (s == girl && se == winter) {
printf("女孩喜欢%s\n", "冬天");
}
else {
printf("无效输入\n");
}
return 0;
}
简单一点的
enum season{Spring, summer, fall, winter, Invaild};
enum season select(void) {
int tmp;
do {
printf("0...Spring 1...summer 2...fall 3...winter 4...结束");
scanf("%d", &tmp);
} while (tmp< Spring || tmp> Invaild);
return tmp;
}
int main(void) {
enum season selected;
do {
switch (selected=select())
{
case Spring:printf("Spring\n");break;
case summer:printf("Summer\n");break;
case fall :printf("Fall\n");break;
case winter:printf("Winter\n");break;
}
} while (selected != Invaild);
return 0;
}
练习8-6
#include <stdio.h>
int factorial(int n) {
int i ;
int sum = 1;
for (i = 1; i <= n; i++) {
sum*=i;
}
return sum;
}
int main() {
int x;
printf("请输入一个数:");
scanf("%d", &x);
printf("它的阶乘是:%d", factorial(x));
}
练习8-7
不认识这个知识点了，网上抄的。
#include <stdio.h>
int factorial(int n)
{
if (n > 0)
return n * factorial(n - 1);
else
return 1;
}
int combination(int n, int r)
{
if (n > 0)
return factorial(n) / (factorial(r) * factorial(n - r));
else
return 1;
}
int main()
{
int n;
int r;
printf("n=");
scanf("%d", &n);
printf("r=");
scanf("%d", &r);
printf("%d", combination(n, r));
return 0;
}
练习8-8
对于这个知识点不理解可以去百度看介绍，方便理解程序
int gcd(int a,int b)
{
int v,sum,n;
if(a < b)
{
v = b;
b = a;
a = v;
}
sum = a%b;
n =a*b;
while(sum != 0)
{
a = b;
b = sum;
sum = a%b;
}
return b;
}
//26/12=2...2
//12/2=6...0
int main()
{
int x,y;
scanf("%d%d",&x,&y);
gcd(x,y);
printf("最大公约数是：%d 最小公倍数是：%d",gcd(x,y),(x*y)/gcd(x,y));
return 0;
}
另一个网络方法
#include <stdio.h>
int gcd(int x, int y)
{
int z;
if (x != y)
{
if (x > y)
x -= y;
else
y -= x;
z = gcd(x, y);
}
else
z = x;
return z;
}
int main()
{
int x, y;
printf("x:");
scanf("%d", &x);
printf("y:");
scanf("%d", &y);
printf("gcd(%d,%d) = %d\n", x, y, gcd(x, y));
return 0;
}
练习8-9
#include <stdio.h>
int main(void)
{
int i = 0;
int linenum = 1;
char ch[128];
while (ch[i] = getchar())
{
if (ch[i] == EOF)
break;
if (ch[i] == '\n')
linenum++;
i++;
}
printf("\nlinenum =%d\n",linenum);
return 0;
}
练习8-10
#include <stdio.h>
int main(void)
{
int i, ch,j;
int cnt[10] = { 0 };
while ((ch = getchar()) != EOF) {
if (ch >= '0' && ch <= '9')
cnt[ch - '0']++;
}
puts("数字字符的出现次数");
for (i = 0; i < 10; i++) {
printf("'%d':", i);
for (j = 0; j < cnt[i]; j++) {
putchar('*');
}putchar('\n');
}
return 0;
}