1 #include <stdio.h>
 2 #include <stdlib.h>
 3 int main()
 4 {
 5     int n = 0;
 6     printf("输入键盘上的字符\n");
 7     while (getchar() !='\n'){
 8         n++;
 9     }
10     printf("%d\n", n);
11     system("pause");
12     return 0;
13 }

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 int main (){
 4     int i = 0;
 5     while (getchar() != '9'){
 6         i++;
 7     }
 8     printf("该系列字符不等于9的个数是\n%d\n", i);
 9     system("pause");
10     return 0;
11 }

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 int main(){
 4     int i = 0;
 5     while (getchar() != '9'){
 6         i++;
 7         if (i == 10){
 8             printf("输入过多\n");
 9             break;
10         }
11     }
12     if (i != 10){
13
14
15         printf("该系列字符不等于9的个数是\n%d\n", i);
16     }
17     system("pause");
18     return 0;
19 }

 1 #define _CRT_SECURE_NO_WARNINGS
 2 #include <stdio.h>
 3 #include <stdlib.h>
 4 #include<string.h>
 5 int main()
 6 {
 7     char a[] = "hi", c[] = "i am teacher!";
 8     strcpy(c,a);
 9     printf("%s\n%s\n", a, c);
10     system("pause");
11     return 0;
12 }

 1 #define _CRT_SECURE_NO_WARNINGS
 2 #include<stdio.h>
 3 #include<stdlib.h>
 4 #include<string.h>
 5 int main(){
 6     int i;
 7     char password[10] = { 0 };
 8     for (i = 1; i <= 3; i++){
 9         printf("请输入密码\n");
10 //        字符数组，scanf时候可以不加&
11         scanf("%s", &password);
12         if (strcmp(password, "100001") == 0){
13             printf("输入正确！\n");
14             printf("正在登陆...\n");
15             break;
16         }
17         else{
18             printf("输入错误，请重试\n");
19             if (i == 3){
20                 printf("重复输入过多,退出登录\n");
21             }
22         }
23     }
24     system("pause");
25     return 0;
26 }