C---------------LessonCircle

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])

{

//initialization: 循环变量初始化,记录循环初始值.

//condition: 循环条件,条件满足执行循环体.

//increment: 循环变量增量.

//statements: 循环体,反复执行的代码.

for (int i = 100; i < 400; i += 5) {

printf("吃第%d次包子\n", i / 5 - 19);

}

//打印一百遍Hello World

//循环次数 = (循环条件 - 初始值) / 增量

for (int i =0; i < 100; i++) {

printf("%d Hello World\n", i + 1);

}

//打印出0 - 100的数

for (int i = 0; i <= 100; i++) {

printf("%d ", i);

}

//打印出0 - 100的偶数

for (int i = 0; i <= 100; i += 2) {

printf("%d ", i);

}

printf("\n");

//打印出0 - 100的奇数

for (int i = 0; i < 100; i += 2) {

printf("%d ", i + 1);

}

for (int i = 0; i <= 100; i++) {

if (i % 2 != 0) {

printf("%d ", i);

}

//打印出1 - 100之间7的倍数

for (int i = 1; i <= 100; i++) {

if (i % 7 == 0) {

printf("%d ", i);

}

//打印出1 - 100之间个位为7的数

for (int i = 1; i <= 100; i++) {

if (i % 10 == 7) {

printf("%d ", i);

}

//取出1234中的3

//i = 1234 / 10 % 10

//打印出1 - 100之间十位为7的数

for (int i = 1; i <= 100; i++) {

if (i / 10 % 10 == 7) {

printf("%d ", i);

}

for (int i = 1; i <= 100; i++) {

if ((i % 7 != 0) && (i / 10 != 7) && (i % 10 != 7)) {

printf("%d ", i);

}

//计算1 - 100的和

int sum = 0;

for (int i = 1; i <= 100; i++) {

sum += i;

}

printf("sum = %d\n", sum);

//计算1 - 100的偶数和,奇数和,7的倍数和,不是7的倍数且不包含7的和

int sum1 = 0, sum2 = 0, sum3 = 0, sum4 = 0;

for (int i = 1; i <= 100; i++) {

if (i % 2 == 0) {

sum1 += i;

} else {

sum2 += i;

}

if (i % 7 == 0) {

sum3 += i;

}

if (i % 7 != 0 && i / 10 != 7 && i % 10 != 7) {

sum4 += i;

}

printf("sum1 = %d\nsum2 = %d\nsum3 = %d\nsum4 = %d\n", sum1, sum2, sum3, sum4);

//循环嵌套

//1.打印一行1 2 3

for (int i = 1; i <= 3; i++) {

printf("%d ", i);

}

printf("\n");

//打印三行1 2 3

for (int i = 1; i <= 3; i++) {

printf("%d ", i);

}

printf("\n");

for (int i = 1; i <= 3; i++) {

printf("%d ", i);

}

printf("\n");

for (int i = 1; i <= 3; i++) {

printf("%d ", i);

}

printf("\n");

//外层循环用来控制1 2 3的行数

for (int i = 0; i < 3; i++) {

//内层循环输出1 2 3

for (int j = 1; j <= i + 1; j++) {

printf("%d ", j);

}

printf("\n");

}

for (int i = 0; i < 3; i++) { // 1 2 3

for (int j = 1; j <= 3 - i; j++) { // 1 2

printf("%d ", j); // 1

}

printf("\n");

}

for (int i = 0; i < 3; i++) { // 3 2 1

for (int j = 3; j >= i + 1; j--) { // 3 2

printf("%d ", j); // 3

}

printf("\n");

}

for (int i = 0; i < 3; i++) { // 3

for (int j = 3; j >= 3 - i; j--) { // 3 2

printf("%d ", j); // 3 2 1

}

printf("\n");

}

// *

// * *

// * * *

//外层循环控制行数

for (int i = 0; i < 3; i++) {

//1.输出空格

for (int j = 0; j < 2 - i; j++) {

printf(" ");

}

//2.输出 *空格

for (int k = 0; k < i + 1; k++) {

printf("* ");

}

printf("\n");

}

// *

// * *

// * * *

// * *

// *

for (int i = 0; i < 5; i++) {

if (i < 3) { //前三行

for (int j = 0; j < 2 - i; j++) {

printf(" ");

}

for (int k = 0; k < i + 1; k++) {

printf("* ");

}

} else { //后两行

for (int j = 0; j < i - 2; j++) {

printf(" ");

}

for (int k = 0; k < 5 - i; k++) {

printf("* ");

}

printf("\n");

}

//输出九九乘法表

//外层循环控制行数

for (int i = 0; i < 9; i++) {

for (int j = 1; j <= i + 1; j++) {

printf("%d*%d=%-4d", i + 1, j, (i + 1) * j);

}

printf("\n");

}

//从控制台输入一个整数,判断该数是否是质数.

int number = 0;

printf("请输入一个整数:\n");

scanf("%d", &number);

//判断一个数是否是质数,只需要看是否能被除了1与它本身之外的数整除即可.

int i = 2;

for ( ; i < number; i++) {

if (number % i == 0) {

printf("该数不是质数\n");

break; //结束本层循环,循环结束

}

if (i == number) {

printf("该数是质数\n");

}

//计算 1 - 100 偶数的和

int sum = 0;

for (int i = 1; i <= 100; i++) {

if (i % 2 != 0) {

continue; //结束本次循环,进入下一次循环

}

sum += i;

}

printf("sum = %d\n", sum);

//while 循环

//1.输出1 - 100之间7的倍数

int i = 1; //循环变量的初始化

while (i < 101) {

if (i % 7 == 0) {

printf("%d ", i);

}

i++; //循环变量增量,不要忘记,如果不写,程序将死循环.

}

//2.从1开始计算,每次加1,直到和大于15时结束,问最后加到几.

int sum = 0; //存储和

int i = 1;

while (sum <= 15) {

sum += i;

i++; //循环变量增量

}

printf("%d\n", i - 1);

//do....while

//1.输出1 - 100之间不是7的倍数,也不包含7的数

int i = 1;

do {

if (i % 7 != 0 && i / 10 != 7 && i % 10 != 7) {

printf("%d ", i);

}

i++; //循环变量增量

} while (i <= 100);

// 总结:

// 循环四部分: 1.循环变量初始化 2.循环条件 3.循环增量 4.循环体

// 执行过程: 1 - 2 - 4 - 3 - 2 - 4 - 3 ---------- 2(循环条件不满足,循环结束)

// for 循环与 while, do..while循环的区别

// for循环多用于知道循环次数.(循环次数确定的情况下)

// while与do...while循环多用于不确定循环次数的需求

// for循环可以转化为 while 与 do...while循环,但是不能反过来.

// while与do...while循环的区别:

// while 先判断循环条件,再执行循环体.

// do...while先执行循环体,再执行循环条件,即使循环条件不满足,循环体也会执行一次.

// 随机值

//1.随机一个小于10的数. [0 9]

// int ran = arc4random() % 10;

//2.随机一个小于20的数. [0 19]

// int ran = arc4random() % 20;

//3.随机一个[5 15]

// int ran = arc4random() % 11 + 5;

//4.随机一个[a b]

// int ran = arc4random() % (b - a + 1) + a;

// printf("ran = %d\n", ran);

return 0;

}

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Homework

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])

{

//******************************************第一题***********************************************

int day = 0;

int money = 1000000000;

while (money > 0) {

money = money / 2;

day++;

}

printf("day = %d\n", day - 1);

//******************************************第二题***********************************************

int number = 0;

int maxnum = 0;

for (int i = 0; i < 20; i++) {

number = arc4random() % 91 + 10;

printf("%d ", number);

if (number > maxnum) {

maxnum = number;

}

printf("\nmaxnum = %d\n", maxnum);

//******************************************第三题************************************************

int num = 0;

for (int i = 1; i < 10; i++) {

for (int j = 0; j < 10; j++) {

for (int k = 0; k < 10; k++) {

if ((i * i * i + j * j * j + k * k * k) == (i * 100 + j * 10 + k)) {

printf("%d%d%d ", i, j, k);

num++;

}

printf("\nnum = %d\n", num);

//******************************************第四题************************************************

for (int a = 0; a < 10; a++) {

for (int b = 0; b < 10; b++) {

for (int c = 0; c < 10; c++) {

if (a * 100 + b * 10 + c + c * 100 + b * 10 + a == 1333) {

printf("a = %d, b = %d, c = %d\n", a, b, c);

}

//******************************************第五题************************************************

int num1 = 0, num2 = 0;

printf("输入两个数:\n");

scanf("%d%d", &num1, &num2);

int gnum1 = num1;

int gnum2 = num2;

int t = 0;

int g = 0;

if (gnum2 > gnum1) {

t = gnum1;

gnum1 = gnum2;

gnum2 = t;

}

while (gnum2 != 0) {

g = gnum1 % gnum2;

gnum1 = gnum2;

gnum2 = g;

}

printf("最大公约数:%d\n", gnum1);

printf("最小公倍数:%d\n", num1 * num2 / gnum1);

int num1 = 0, num2 = 0;

int i = 0;

printf("输入两个数:\n");

scanf("%d%d", &num1, &num2);

for (i = num1; ; i--) {

if (num1 % i == 0 && num2 % i == 0) {

break;

}

printf("最大公约数:%d\n最小公倍数:%d\n", i, num1 * num2 / i);

//*****************************************第六题*************************************************

int n = 0;

long num = 0;

long minnum = 0;

printf("位数:\n");

scanf("%d", &n);

int i = 0;

do {

num = arc4random();

if (minnum == 0 && i == 0) {

minnum = num;

}

printf("%ld ", num);

if (minnum > num) {

minnum = num;

}

i++;

} while (i < n);

printf("\n最小值:%ld\n", minnum);

int n = 0;

long num = 0;

long minum = 0;

printf("位数:\n");

scanf("%d", &n);

int i = 0;

do {

num = arc4random();

if (i == 0) {

minum = num;

} else if (minum > num){

minum = num;

}

printf("%ld ", num);

i++;

} while (i < n);

printf("\n最小值: %ld\n", minum);

return 0;

}

C---------------LessonCircle

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