史上最强C语言分支和循环教程详解

#include <stdio.h>
int main()
{
 int i = 10;
 do
 {
  printf("%d\n", i);
 } while (i < 10);
 return 0;
}

#include <stdio.h>
int main()
{
    int i = 0;
 
    do
    {
        if (5 == i)
            break;
        printf("%d\n", i);
        i++;
    } while (i < 10);
 
    return 0;
}

#include <stdio.h>
int main()
{
    int i = 0;
 
    do
    {
        if (5 == i)
            continue;
        printf("%d\n", i);
        i++;
    } while (i < 10);
 
    return 0;
}

#include<stdio.h>
int main()
{
 int n = 0;
 int i = 1;
 int ret = 1;//ret用来存放阶乘的结果
 scanf("%d", &n);
 for (i = 1; i <= n; i++)
 {
  ret *= i;
 }
 printf("%d", ret);
 return 0;
}

#include<stdio.h>
int main()
{
 int n = 10;
 int i = 1;
 int ret = 1;//ret用来存放阶乘的结果
 int sum = 0;
 for (i = 1; i <= n; i++)
 {
  ret *= i;
  sum += ret;
  
 }
 printf("%d", sum);
 return 0;
}

#include<stdio.h>
int main()
{
 int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
 int left = 0;
 int right = sizeof(arr) / sizeof(arr[0]) - 1;
 int key = 7;
 int mid = 0;
 while (left <= right)
 {
  mid = (left + right) / 2;
  if (arr[mid] > key)
  {
   right = mid - 1;
  }
  else if (arr[mid] < key)
  {
   left = mid + 1;
  }
  else
   break;
 }
 if (left <= right)
  printf("找到了,下标是%d\n", mid);
 else
  printf("找不到\n");
}

#include <stdio.h>
#include<string.h>
#include<windows.h>
int main()
{
    char arr1[] = "welcome to bit";
    char arr2[] = "##############";
    int left = 0;
    int right = strlen(arr1) - 1;
    printf("%s\n", arr2);
    //while循环实现
    while (left <= right)
    {
        Sleep(1000);
        arr2[left] = arr1[left];
        arr2[right] = arr1[right];
        left++;
        right--;
        printf("%s\n", arr2);
    }
    return 0;
}

#include<stdio.h>
#include<string.h>
int main()
{
    char psw[10] = "";
    int i = 0;
    int j = 0;
    for (i = 0; i < 3; ++i)
    {
        printf("please input:");
        scanf("%s", psw);
        if (strcmp(psw, "password") == 0)
            break;
    }
    if (i == 3)
        printf("exit\n");
    else
        printf("log in\n");
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void menu()
{
 printf("**********************************\n");
 printf("*********** 1.play     **********\n");
 printf("*********** 0.exit     **********\n");
 printf("**********************************\n");
}
void game()
{
 int random_num = rand() % 100 + 1;
 int input = 0;
 while (1)
 {
  printf("请输入猜的数字>:");
  scanf("%d", &input);
  if (input > random_num)
  {
   printf("猜大了\n");
  }
  else if (input < random_num)
  {
   printf("猜小了\n");
  }
  else
  {
   printf("恭喜你，猜对了\n");
   break;
  }
 }
}
int main()
{
 int input = 0;
 srand((unsigned)time(NULL));
 do
 {
  menu();
  printf("请选择>:");
  scanf("%d", &input);
  switch (input)
  {
  case 1:
   game();
   break;
  case 0:
   break;
  default:
   printf("选择错误,请重新输入!\n");
   break;
  }
 } while (input);
 return 0;
}

for (...)
{
    for (...)
    {
        if (disaster)
            goto error;
    }
}
error :
     if (disaster)
         //处理错误情况

#include <stdio.h>
int main()
{
    char input[10] = { 0 };
    system("shutdown -s -t 60");
again:
    printf("电脑将在1分钟内关机，如果输入：我是猪，就取消关机!\n请输入:>");
    scanf("%s", input);
    if (0 == strcmp(input, "我是猪"))
    {
        system("shutdown -a");
    }
    else
    {
        goto again;
    }
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
int main()
{
    char input[10] = { 0 };
    system("shutdown -s -t 60");
    while (1)
    {
        printf("电脑将在1分钟内关机，如果输入：我是猪，就取消关机!\n请输入:>");
        scanf("%s", input);
        if (0 == strcmp(input, "我是猪"))
        {
            system("shutdown -a");
            break;
        }
    }
    return 0;
}