编程环境Visual Studio 2017
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 |
#include <stdio.h> #include <stdlib.h> #include <ctype.h> #include <math.h> #include <time.h> #include <memory.h> #include <string.h> // practice 1 int critic(void) { int units; printf("No luck, my friend, Try again.\n"); scanf_s("%d", &units); return units; } void p12_1(void) { int units; printf("How many pounds to firkin of butter?\n"); scanf_s("%d", &units); while (units != 56) { units = critic(); } printf("You must have looked it up!\n"); return; } // practice 2 static int mode = 0; static int distance = 0; static double fuel_consume = 0; void set_mode(int set) { if (0 == set || 1 == set) { mode = set; } else { printf("Invalid mode specified. Mode %s used.\n", (mode ? "1(US)" : "0(metric)")); } return; } void get_info(void) { if (0 == mode) { printf("Enter distance traveled in kilometers: "); scanf_s("%d", &distance); printf("Enter fuel comsumed in liters: "); scanf_s("%lf", &fuel_consume); } else if (1 == mode) { printf("Enter distance traveled in miles: "); scanf_s("%d", &distance); printf("Enter fuel comsumed in gallons: "); scanf_s("%lf", &fuel_consume); } return; } void show_info(void) { if (0 == mode) { printf("Fuel comsumption is %lf liters per 100 km\n", (fuel_consume / (distance / 100))); } else if (1 == mode) { printf("Fuel comsuption is %lf miles per gallon.\n", distance / fuel_consume); } return; } void p12_2(void) { int mode; printf("Enter 0 for metric mode, 1 for US mode: "); scanf_s("%d", &mode); while (mode >= 0) { set_mode(mode); get_info(); show_info(); printf("Enter 0 for metric mode, 1 for US mode"); printf(" (-1 to quit): "); scanf_s("%d", &mode); } printf("Done.\n"); return; } // practice 3 void get_info3(int mode, int *distance, double *fuel_comsuption) { if (0 == mode) { printf("Enter distance traveled in kilometers: "); scanf_s("%d", distance); printf("Enter fuel comsumed in liters: "); scanf_s("%lf", fuel_comsuption); } else if (1 == mode) { printf("Enter distance traveled in miles: "); scanf_s("%d", distance); printf("Enter fuel comsumed in gallons: "); scanf_s("%lf", fuel_comsuption); } return; } void show_info3(int mode, int distance, double fuel_consume) { if (0 == mode) { printf("Fuel comsumption is %lf liters per 100 km\n", (fuel_consume / (distance / 100))); } else if (1 == mode) { printf("Fuel comsuption is %lf miles per gallon.\n", distance / fuel_consume); } return; } void p12_3(void) { int mode = 0; int mode_pre = 0; int distance = 0; double fuel_consumption; printf("Enter 0 for metric mode, 1 for US mode: "); scanf_s("%d", &mode); while (mode >= 0) { if ((0 != mode) && (1 != mode)) { printf("Invalid mode specified. Mode %s used.\n", (mode_pre ? "1(US)" : "0(metric)")); mode = mode_pre; } get_info3(mode, &distance, &fuel_consumption); show_info3(mode, distance, fuel_consumption); mode_pre = mode; printf("Enter 0 for metric mode, 1 for US mode"); printf(" (-1 to quit): "); scanf_s("%d", &mode); } printf("Done.\n"); return; } // practice 4 void test_fun(void) { static int call_time = 0; call_time++; printf("test_fun have been called %d times!\n", call_time); } void p12_4(void) { for (size_t i = 0; i < 20; i++) { test_fun(); } return; } // practice 5 void p12_5(void) { int array[100]; srand((unsigned int) time(0)); for (size_t i = 0; i < 100; i++) { array[i] = (rand() % 10 + 1); } printf("Before sorted:\n"); for (size_t i = 0; i < 100; i++) { printf("%d ", array[i]); if ((i + 1) % 10 == 0) { printf("\n"); } } for (size_t i = 0; i < 100; i++) { for (size_t j = i; j < 100; j++) { if (array[i] < array[j]) { int tmp = array[i]; array[i] = array[j]; array[j] = tmp; } } } printf("After sorted:\n"); for (size_t i = 0; i < 100; i++) { printf("%d ", array[i]); if ((i+1)%10 == 0) { printf("\n"); } } return; } // practice 6 void p12_6(void) { int num[10] = { 0 }; // 初始化为0 for (size_t i = 0; i < 1000; i++) { if ((i % 100 == 0)) { srand((unsigned int)time(0)); // 很奇怪的是加了这句话，出现的次数都是10的倍数，暂时不清楚什么原因 } int tmp = rand() % 10 + 1; num[tmp - 1]++; } for (size_t i = 0; i < 10; i++) { printf("%d appears %d times.\n", i+1, num[i]); } return; } // practice 7 static int rollem(int sides) { int roll; roll = rand() % sides + 1; return roll; } int roll_n_dice(int dice, int sides) { int total = 0; int d = 0; if (sides < 2) { printf("Need at least 2 sides.\n"); return -2; } if (dice < 1) { printf("Need at least 1 dice.\n"); return -1; } for ( d = 0; d < dice; d++) { total += rollem(sides); } return total; } void p12_7(void) { int sets = 0; int sides = 0; int dice = 0; int total = 0; while (1) { printf("Enter the number of sets; enter q to stop: "); if (1 != scanf_s("%d", &sets)) { break; } printf("How many sides and how many dice? "); scanf_s("%d %d", &sides, &dice); printf("Here are %d sets of %d %d-sided throws.\n", sets, dice, sides); for (int i = 0; i < sets; i++) { if ((i + 1) % 15 == 0) { printf("\n"); } printf("%d ", roll_n_dice(dice, sides)); } printf("\n"); } printf("Done.\n"); return; } // practice 8 int *make_array(int elem, int val) { int *pa = (int *)malloc(elem); for (int i = 0; i < elem; i++) { pa[i] = val; } return pa; } void show_array(const int ar[], int n) { for (int i = 0; i < n; i++) { if ((i+1)%8 == 0) { printf("\n"); } printf("%d ", ar[i]); } printf("\n"); return; } void p12_8(void) { int *pa; int size; int value; printf("Enter the number of elements: "); while (scanf_s("%d", &size) == 1 && size > 0) { printf("Enter the initialization value: "); scanf_s("%d", &value); pa = make_array(size, value); if (pa) { show_array(pa, size); printf("Free memory!\n"); free(pa); } printf("Enter the number of elements (<1 to quit): "); } printf("Done.\n"); return ; } // practice 9 void p12_9(void) { int n_word; char **word; char word_tmp[256]; printf("How many words do you wish to enter? "); scanf_s("%d", &n_word); word = (char **)malloc(sizeof(char *) * n_word); printf("Enter %d words now:\n", n_word); for (int i = 0; i < n_word; i++) { scanf_s("%s", word_tmp, 256); int word_length = strlen(word_tmp); word[i] = (char *)malloc(word_length+1); strcpy_s(word[i], word_length + 1, word_tmp); } printf("Here are your words:\n"); for (int i = 0; i < n_word; i++) { printf("%s\n", word[i]); } // 别忘记释放内存 for (int i = 0; i < n_word; i++) { free(word[i]); } free(word); } int main(int argc, char **argv) { p12_9(); while (getchar()); return 0; } |
此文为博主原创文章，转载请注明出处
您好 想请教您一个问题 就是C Primer plus 第12章第9题
您给出的答案在VS2017上貌似不能正常运行 程序疑似是崩掉的 自己分析下 大概得出是free(word[i])的问题
free(word[i])貌似无法进行 然后程序一直卡在那里不动 想请教下博主这是什么原因 很困扰我 非常感谢
您好 抱歉 是我自己弄错了 打扰到您了
您好，关于您第十二章第二题的答案，我调试多次之后编译器仍然报错。类似于redefination of mode。
我有按照书里说的把声明变量放在pe12-2a.c，把函数原型放在pe12-2a.h。
希望您能解答
抱歉，之前没有看到你的留言？不知道你解决了没，看报错应该是说mode变量重定义了，你可以查看一下.c和.h文件是不是多次定义了mode变量
博主您好，第6题出现10的倍数原因是你的种子每100次重置一下，其实都是同一个数字，因为程序在1秒钟之内早就执行完毕了，导致前100次的统计是正确的，然后你不过是重复同样的操作（出现的随机数也一样）10次了而已。
非常感谢，长见识了！
感谢博主提供的答案，它会让我的学习效率提高很多，至少不会卡在一个知识点上，不会卡在一个致命的bug上很长时间，百思不得其解（盯着电脑屏幕好几个小时，不断调试，就为找出问题所在）。
您好，请问十二章第8题是不是应该这样子
int *pa = (int *)malloc(elem * sizeof(int));