实现九九乘法表

// 输出乘法口诀表 
int main()
{int i = 0;int j = 0;for (i = 1; i <= 9; i++){for (j = 1; j <= i;j++)printf("%d*%d=%d ", i , j, i*j);printf("\n");
}return 0;
}

猜数字的游戏设计

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<time.h>// 猜数字 
// 用时间戳函数的形式 void menu();
void game();
int main()
{int  input  = 0;srand((unsigned int)time(NULL));do{menu();printf("请选择>:");scanf("%d", &input);switch(input){case 1: game();break;case 0 :printf("退出游戏\n");break;default : printf("输入错误\n");break;}} while (input);return 0;
}
void menu()
{printf("**************************\n");printf("**************************\n");printf("*****请开始你的选择*******\n");printf("   1.begin       0.end    \n");printf("**************************\n");printf("**************************\n");printf("**************************\n");printf("**************************\n");
}
void game()
{int a = 0;int b = 0;a = rand() % 100 + 1; // 取1到100以内的数字while (1){printf("请输入您想要输入的数字：\n");scanf("%d", &b);if (b < a){printf("猜小了\n");}else if (b > a){printf("猜大了\n");}else{printf("恭喜你猜对了\n");printf("   ***   ***\n");printf("  ***** *****\n");printf("  ***********\n");printf("   *********\n");printf("    *******\n");printf("      ***\n");break;}}
}

素数判断

// 素数判断
#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<time.h>//素数判断
int panduan(int input);
int main()
{int input = 0;printf("请输入想要的数字：\n");scanf("%d", &input); // 得到输入inputint a = panduan(input);if (a == 0){printf("不是 素数\n");}else {printf("是 素数 ！");}return 0;
}
int panduan(int input)
{int i = 0; for (i = 2; i < input; i++){if (input %i == 0){return 0;}}return 1;
}

有序数组的查找

// 有序数组的查找
#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<time.h>// 有序数组的查找
int chaozhao(int arr[], int n, int sz);
int main()
{int n = 0;int arr[] = { 1,2,3,4,5,6,7,8,9,10,11 };int sz = sizeof(arr) / sizeof(arr[0]);printf("请输入数字：\n");scanf("%d", &n);int b=  chazhao( arr, n, sz);if (b == 0){printf("没找到");}else{printf("找到了并且下标是%d\n", b);}return 0;
}int chazhao(int arr[], int n, int sz)
{int left = 0;int right = sz - 1; while (left <= right){int mid = (left + right) / 2;if (n > arr[mid]){left = mid + 1;}else if (n < arr[mid]){right = mid - 1;}elsereturn mid;}return 0;
}

有序打印数字既递归的学习

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<time.h>// 递归的简易设计
// 
void digui(int a);
int main()
{int input  =  0;printf("请输入想要输入的数字\n");scanf("%d", &input);digui(input); return 0;
}void digui(int n)
{if (n > 9){digui(n / 10);}printf("%d ", n%10);
}