1 #define _CRT_SECURE_NO_WARNINGS 1
  2 #include <stdio.h>
  3 #include <stdlib.h>
  4 #include <string.h>
  5 #include <assert.h>
  6 int main()
  7 {
  8     unsigned char a = 200;
  9     unsigned char b = 100;
 10     unsigned char c = 0;
 11     c = a + b;
 12     printf("%d %d", a + b , c);//整型提升问题
 13     system("pause");
 14     return 0;
 15 }
 16 
 17 int main()
 18 {
 19     //在32位大端模式处理器下变量b等于( )
 20     unsigned int a = 0x1234;
 21     unsigned char b = *(unsigned char *)&a;
 22     printf("%d\n", b);
 23     system("pause");
 24     return 0;
 25 }
 26 
 27 int main()
 28 {
 29     char a[1000] = { 0 };
 30     int i = 0;
 31     for (i = 0; i < 1000; i++)
 32     {
 33         a[i] = -1 - i;
 34     }
 35     printf("%d\n", strlen(a));//255
 36     system("pause");
 37     return 0;
 38 }
 39 
 40 杨辉三角形
 41 int main()
 42 {
 43     int arr[10][10] = { 0 };
 44     int i = 0;
 45     int j = 0;
 46     for (i = 0; i < 10; i++)
 47     {
 48         for (j = 0; j < 10; j++)
 49         {
 50             if (j == 0)
 51             {
 52                 arr[i][j] = 1;
 53             }
 54             if (i == j)
 55             {
 56                 arr[i][j] = 1;
 57             }
 58             //计算中间的数
 59             if (i >= 2 && j >= 1)
 60             {
 61                 arr[i][j] = arr[i - 1][j] + arr[i - 1][j - 1];
 62             }
 63         }
 64     }
 65     //打印
 66     for (i = 0; i < 10; i++)
 67     {
 68         for (j = 0; j <= i; j++)
 69         {
 70             printf("%d ", arr[i][j]);
 71         }
 72         printf("\n");
 73     }
 74     system("pause");
 75     return 0;
 76 }
 77 
 78 猜凶手
 79 int main()
 80 {
 81     int killer = 0;
 82     for (killer = 'a'; killer <= 'd'; killer++)
 83     {
 84         if ((killer != 'a') + (killer == 'c') + (killer == 'd') + (killer != 'd') == 3)
 85         {
 86             printf("killer = %c\n", killer);
 87         }
 88     }
 89     system("pause");
 90     return 0;
 91 }
 92 
 93 int main()
 94 {
 95     int a = 0;
 96     int b = 0;
 97     int c = 0;
 98     int d = 0;
 99     int e = 0;
100     for (a = 1; a <= 5; a++)
101     {
102         for (b = 1; b <= 5; b++)
103         {
104             for (c = 1; c <= 5; c++)
105             {
106                 for (d = 1; d <= 5; d++)
107                 {
108                     for (e = 1; e <= 5; e++)
109                     {
110                         if (((b == 2) + (a == 3) == 1) &&
111                             ((b == 2) + (e == 4) == 1) &&
112                             ((c == 1) + (d == 2) == 1) &&
113                             ((c == 5) + (d == 3) == 1) &&
114                             ((e == 4) + (a == 1) == 1))
115                         {
116                             if (a*b*c*d*e == 120)
117                             {
118                                 printf("a=%d,b=%d,c=%d,d=%d,e=%d\n", a, b, c, d, e);
119                             }
120                             
121                         }
122                     }
123                 }
124             }
125         }
126     }
127     system("pause");
128     return 0;
129 }
130 
131 int main()
132 {
133     //申请空间
134     int *p = (int*)malloc(10 * sizeof(int));
135     //使用空间
136 
137     //释放空间
138     free(p);
139     system("pause");
140     return 0;
141 }
142 
143 int main()
144 {
145     char str1[] = "hello bit.";
146     char str2[] = "hello bit.";
147     char *str3 = "hello bit.";
148     char *str4 = "hello bit.";
149     if (str1 == str2)
150     {
151         printf("str1 and str2 are same\n");
152     }
153     else{
154         printf("str1 and str2 are not same\n");
155     }
156     if (str3 == str4)
157     {
158         printf("str3 and str4 are same\n");
159     }
160     else{
161         printf("str3 and str4 are not same\n");
162     }
163     system("pause");
164     return 0;
165 }
166 
167 int main()
168 
169 {
170     int a[5] = { 5, 4, 3, 2, 1 };
171     int *ptr = (int *)(&a + 1);
172     printf("%d,%d\n", *(a + 1), *(ptr - 1));
173     system("pause");
174     return 0;
175 }
176 
177 int main()
178 {
179     int aa[2][5] = { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 };
180     int *ptr1 = (int *)(&aa + 1);
181     int *ptr2 = (int *)(*(aa + 1));
182     printf("%d,%d\n", *(ptr1 - 1), *(ptr2 - 1));
183     system("pause");
184     return 0;
185 }
186 
187 //字符串左旋(旋转字符串) - 方法一 - 暴力求解法
188 //形参是数组实现
189 void left_move(char arr[],int k)
190 {
191     
192 }
193 //形参是指针实现
194 void left_move(char* arr, int k)
195 {
196     assert(arr!=NULL);//断言
197     int i = 0;
198     int len = strlen(arr);
199     for (i = 0; i < k; i++)
200     {
201         //左旋转一个字符
202         char tmp = *arr;
203         int j = 0;
204         for (j = 0; j < len-1; j++)
205         {
206             *(arr + j) = *(arr + j + 1);
207         }
208         *(arr + len - 1) = tmp;
209     }
210 }
211 int main()
212 {
213     char arr[] = "abcdef";
214     left_move(arr, 2);
215     printf("%s\n", arr);
216     system("pause");
217     return 0;
218 }
219 
220 void reverse(char* left, char* right)
221 {
222     assert(left != NULL);
223     assert(right != NULL);
224     while (left<right)
225     {
226         char tmp = *left;
227         *left = *right;
228         *right = tmp;
229         left++;
230         right++;
231     }
232 }
233 void left_move(char* arr, int k)
234 {
235     assert(arr);//指针断言
236     int len = strlen(arr);
237     assert(k <= len);//断言，防止越界
238     reverse(arr,arr+k-1);//逆序左边
239     reverse(arr+k,arr+len-1);//逆序右边
240     reverse(arr,arr+len-1);//逆序整体
241 }
242 //方法二 - 三步翻转法
243 int main()
244 {
245     char arr[] = "abcdef";
246     left_move(arr, 2);
247     printf("%s\n", arr);
248     system("pause");
249     return 0;
250 }
251 
252 //判断字符串是否旋转后得到另一个字符串
253 //把所有可能性都列出来
254 int is_left_move(char* s1, char* s2)
255 {
256     int len = strlen(s1);
257     int i = 0;
258     for (i = 0; i < len; i++)
259     {
260         left_move(s1,1);
261         int ret = strcmp(s1, s2);
262         if (ret == 0)
263         {
264             return 1;
265         }
266     }
267     //所有字符比完后再整体判断是否相等
268     return 0;
269 }
270 int main()
271 {
272     char arr1[] = "abcdef";
273     char arr2[] = "cdefab";
274     int ret = is_left_move(arr1, arr2);
275     if (ret == 1)
276     {
277         printf("yes\n");
278     }
279     else{
280         printf("no\n");
281     }
282     system("pause");
283     return 0;
284 }
285 
286 
287 int is_left_move(char* str1,char* str2)
288 {
289     int len1 = strlen(str1);
290     int len2 = strlen(str2);
291     if (len1 != len2)
292     {
293         return 0;
294     }
295     //1.在str1字符串中追加一个str1字符串
296     strncat(str1, str2, 6);
297     //2.判断str2指向的字符串是否是str1指向的字符串的子串
298     //strstr() - 找字串的函数
299     char * ret = strstr(str1, str2);
300     if (ret == NULL)
301     {
302         return 0;
303     }
304     else{
305         return 1;
306     }
307 }
308 int main()
309 {
310     char arr1[30] = "abcdef";
311     char arr2[] = "cdefab";
312     int ret = is_left_move(arr1,arr2);
313     if (ret == 1)
314     {
315         printf("yes\n");
316     }
317     else{
318         printf("no\n");
319     }
320     system("pause");
321     return 0;
322 }
323 
324 int main()
325 {
326 
327     system("pause");
328     return 0;
329 }
330 
331 杨氏矩阵
332 int FindNum(int arr[3][3], int k,int *px,int *py)
333 {
334     int x = 0;
335     int y = *px - 1;
336     while (x<=*py-1 && y>=0)
337     {
338         if (arr[x][y] > k)
339         {
340             y--;
341         }
342         else if (arr[x][y]<k)
343         {
344             x++;
345         }
346         else{
347             *px = x;
348             *py = y;
349             return 1;
350         }
351     }
352     //找不到
353     *px = -1;
354     *py = -1;
355     return 0;
356 }
357 int main()
358 {
359     int arr[3][3] = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };
360     int k = 7;
361     int x = 3;
362     int y = 3;
363     //返回型参数
364     int ret = FindNum(arr, k, &x, &y);
365     if (ret == 1)
366     {
367         printf("找到了\n");
368         printf("%d %d\n", x, y);
369         printf("%p %p\n", x, y);
370     }
371     else{
372         printf("找不到\n");
373     }
374     system("pause");
375     return 0;
376 }
377 
378 
379 
380 //1.计数器方法
381 //2.递归方法
382 //3.指针-指针方法
383 
384 //size_t my_strlen(const char* str)
385 int my_strlen(const char* str)
386 {
387     int count = 0;
388     assert(str != NULL);//断言,字符串不能为空
389     while (*str != '\0')// == while(*str)
390     {
391         count++;
392         str++;
393     }
394     return count;
395 }
396 int main()
397 {
398     int len = my_strlen("abcdef");
399     //int arr[] = { 'a', 'b', 'c', 'd', 'e', 'f','\0' };
400     //int len1 = strlen(arr);
401     printf("%d\n",len);
402     //printf("%d\n", len1);
403     system("pause");
404     return 0;
405 }
406 
407 
408 int main()
409 {
410     //size_t = unsigned int = 无符号整型
411     if (strlen("abc") - strlen("abcdef") > 0)
412     {
413         printf("hehe\n");
414     }
415     else{
416         printf("haha\n");
417     }
418     system("pause");
419     return 0;
420 }