这些天真的好忙啊，真的太讨厌早8的课了，特别是早8的外专课！(´-ι_-｀)
练习2-1
//List 2-5 是一个用秒数来表示程序开始后经过的时间的程序。请改写程序，令其不仅能用秒数，还能用时钟数来表示时间。 #include <time.h> #include <stdio.h> /*--- 等待x毫秒 ---*/ int sleep(unsigned long x) { clock_t c1 = clock(), c2; do { if ((c2 = clock()) == (clock_t)-1) /* 错误 */ return 0; } while (1000.0 * (c2 - c1) / CLOCKS_PER_SEC < x); return 1; } int main(void) { int i; clock_t c; for (i = 10; i > 0; i--) { /* 倒数 */ printf("\r-", i); fflush(stdout); sleep(1000); /* 暂停1秒 */ } printf("\r\aFIRE!!\n"); c = clock(); printf("程序开始运行后经过了%.1f秒。\n时钟数为%.1f。\n", (double)c / CLOCKS_PER_SEC,(double)c); return 0; }练习2-2
//编写一个函数，令其能从字符串开头逐一显示字符。 void gput (const char *s, int speed); #include <time.h> #include <stdio.h> #include <string.h> int sleep (unsigned long x) { clock_t c1 = clock(), c2; do { if ( (c2=clock())==(clock_t)-1 ) //(clock_t)-1 是 clock_t型的-1 return 0; } while (1000.0*(c2-c1)/CLOCKS_PER_SEC < x); //注意是CLOCKS不是CLOCK！！！ return 1; } void gput (const char *s, int speed) { int len=strlen(s); int i; for (i=0; i<len; i++) { putchar(s[i]); fflush(stdout); sleep(speed); } } int main(void) { char a[]="Ice Bear Loves Isabel!"; int speed = 500; gput(a,speed); return 0; }练习2-3
//编写一个闪烁显示字符串的函数。 void bput (const char *s, int d, int e, int n); #include <time.h> #include <stdio.h> #include <string.h> int sleep (unsigned long x) { clock_t c1 = clock(), c2; do { if ( (c2=clock())==(clock_t)-1 ) return 0; } while (1000.0*(c2-c1)/CLOCKS_PER_SEC < x); return 1; } void bput (const char *s, int d, int e, int n) { int i,j; int len = strlen(s); for (i=0; i<n; i++) { printf("\r%s",s); //一次性显示字符串，注意输出\r回到本行开头 fflush(stdout); sleep(d); putchar('\r'); //一次性显示相等长度的空格覆盖，注意输出\r回到本行开头 for (j=0; j<len; j++) { printf(" "); fflush(stdout); } sleep(e); } } int main(void) { char a[]="Ice Bear Loves Isabel!"; int d = 100; int e = 100; int n = 100; bput(a,d,e,n); return 0; }练习2-4
//编写一个如字幕般显示字符串的函数。void telop (const char *s, int direction, int speed, int n); #include <time.h> #include <stdio.h> #include <string.h> int sleep (unsigned long x) { clock_t c1 = clock(), c2; do { if ( (c2=clock())==(clock_t)-1 ) return 0; } while (1000.0*(c2-c1)/CLOCKS_PER_SEC < x); return 1; } void telop (const char *s, int direction, int speed, int n) { int i,num=0,cnt=0; int s_len = strlen(s); while(1) { putchar('\r'); for (i=0; i < s_len; i++) { if (cnt+i < s_len) putchar(s[cnt+i]); else putchar(s[cnt+i-s_len]); } fflush(stdout); sleep(speed); if (direction == 0) { //从右往左 if(cnt < s_len-1) cnt ++; else { cnt = 0; num ++; } } else { //从左往右 if(cnt > 0) cnt --; else { cnt = s_len-1; num ++; } } if (num > n) //num为计数变量，每次下标cnt归零是num++，num超过n时即跳出循环 break; } } int main(void) { char s[]="Ice Bears Wants To Sleep "; //注意多加一个空格 int direction; int speed = 500; int n = 5; zmfx: printf("字幕滚动方向：0---从右往左 1---从左往右："); scanf("%d",&direction); if (direction != 0 && direction != 1) { printf("error!\n"); goto zmfx; } telop(s,direction,speed,n); return 0; }练习2-5
//List 2-3 的“心算训练”程序显示的是进行10次加法运算所需要的时间。改写程序，令其能显示每次运算所需要的时间和运算的平均时间。 #include <time.h> #include <stdio.h> int main(void) { int stage; int a, b, c; /* 要进行加法运算的数值 */ int x; /* 已读取的值 */ int n; /* 空白的宽度 */ clock_t start, end; /* 开始时间·结束时间 */ float time1,time_sum=0; srand(time(NULL)); /* 设定随机数的种子 */ printf("扩大视野心算训练开始!!\n"); for (stage = 0; stage < 10; stage++) { a = 10 + rand() % 90; /* 生成10～99的随机数 */ b = 10 + rand() % 90; /* 〃 */ c = 10 + rand() % 90; /* 〃 */ n = rand() % 17; /* 生成0～16的随机数 */ start = clock(); printf("%d%*s+%*s%d%*s+%*s%d：", a, n, "", n, "", b, n, "", n, "", c); do { scanf("%d", &x); if (x == a + b + c) { end = clock(); break; } printf("\a回答错误。请重新输入："); } while (1); time1 = (double)(end - start) / CLOCKS_PER_SEC; time_sum += time1; printf("此次用时%.1f秒。\n\n",time1); } printf("恭喜通关，共用%.1f秒，平均每题%.1f秒。\n",time_sum, time_sum/10); return 0; }练习2-6
//把上面的程序改写成能进行加法和减法运算的程序，每次随机决定进行哪种运算。也就是说，假设三个值是a、b、c，每次都通过随机数来从下列组合中选一个进行出题。 #include <time.h> #include <stdio.h> int main(void) { int stage; int a, b, c; int x; int n, m, answer; clock_t start, end; float time1,time_sum=0; srand(time(NULL)); printf("扩大视野心算训练开始!!\n"); for (stage = 0; stage < 10; stage++) { a = 10 + rand() % 90; b = 10 + rand() % 90; c = 10 + rand() % 90; n = rand() % 17; m = rand() % 4; //生成0~3的随机数 printf("\n%d\n",m); if (m == 0) { printf("%d%*s+%*s%d%*s+%*s%d：", a, n, "", n, "", b, n, "", n, "", c); answer = a+b+c; } else if (m == 1) { printf("%d%*s+%*s%d%*s-%*s%d：", a, n, "", n, "", b, n, "", n, "", c); answer = a+b-c; } else if (m == 2) { printf("%d%*s-%*s%d%*s+%*s%d：", a, n, "", n, "", b, n, "", n, "", c); answer = a-b+c; } else { printf("%d%*s-%*s%d%*s-%*s%d：", a, n, "", n, "", b, n, "", n, "", c); answer = a-b-c; } start = clock(); do { scanf("%d", &x); if (x == answer ) { end = clock(); break; } printf("\a回答错误。请重新输入："); } while (1); time1 = (double)(end - start) / CLOCKS_PER_SEC; time_sum += time1; printf("此次用时%.1f秒。\n\n",time1); } printf("恭喜通关，共用%.1f秒，平均每题%.1f秒。\n",time_sum, time_sum/10); return 0; }