1 #define _CRT_SECURE_NO_WARNINGS 1
2 #include
3 #include
4 #include <string.h>
5 #include
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 }