复习：
取余（求模数）可以生成 任意指定范围随机数，乃“神器”之一
应用：小学生计算测试系统
问题描述：
1 #include "stdafx.h" 2 #include3 #include 4 5 6 int main() 7 { 8 int a, b, c, answer, quotient, remainder, score(0); 9 char ch = '\0'; 10 srand(time(0)); 11 12 printf("Are you ready kids?(Press Enter)"); 13 scanf_s("%c", &ch); 14 15 if (ch =='\n') 16 { 17 printf("\n"); 18 printf("Start!\n\n"); 19 20 21 for (int i = 1; i <= 10; i++) 22 { 23 //产生随机数和随机运算符 24 25 c = rand() % 4; 26 27 switch (c) 28 { 29 30 case 0: 31 while (1) 32 { 33 a = rand()%100 + 1; 34 b = rand()%100 + 1; 35 36 if (a + b > 100) 37 { 38 continue; 39 } 40 else 41 { 42 printf("Qustion Number %u: %u + %u = ?\n", i, a, b); 43 printf("answer : "); 44 scanf_s("%u", &answer); 45 if (answer == a + b) 46 { 47 printf("√\n\a"); 48 score++; 49 } 50 else 51 { 52 printf("×\n"); 53 } 54 printf("\n"); 55 break; 56 } 57 } 58 break; 59 60 61 case 1: 62 while (1) 63 { 64 a = rand() % 100 + 1; 65 b = rand() % 100 + 1; 66 67 if (a < b || a > 100) 68 { 69 continue; 70 } 71 else 72 { 73 printf("Qustion Number %u: %u - %u = ?\n", i, a, b); 74 printf("answer : "); 75 scanf_s("%u", &answer); 76 if (answer == a - b) 77 { 78 printf("√\n\a"); 79 score++; 80 } 81 else 82 { 83 printf("×\n"); 84 } 85 printf("\n"); 86 break; 87 } 88 } 89 break; 90 91 92 case 2: 93 while (1) 94 { 95 a = rand() % 100 + 1; 96 b = rand() % 100 + 1; 97 98 if (a*b > 100) 99 {100 continue;101 }102 else103 {104 printf("Qustion Number %u: %u × %u = ?\n", i, a, b);105 printf("answer : ");106 scanf_s("%u", &answer);107 108 if (answer == a * b)109 {110 printf("√\n\a");111 score++;112 }113 else114 {115 printf("×\n");116 }117 printf("\n");118 break;119 }120 121 }122 break;123 124 125 case 3:126 while (1)127 {128 a = rand() % 100 + 1;129 b = rand() % 100 + 1;130 131 if (a 100)132 {133 continue;134 }135 else136 {137 printf("Qustion Number %u: %u ÷ %u = ?\n", i, a, b);138 printf("quotient : ");139 scanf_s("%u", "ient);140 printf("remainder : ");141 scanf_s("%u", &remainder);142 143 if (quotient == a / b && remainder == a % b)144 {145 printf("√\n\a");146 score++;147 }148 else149 {150 printf("×\n");151 }152 printf("\n");153 break;154 }155 }156 break;157 158 default:159 break;160 }161 }162 163 printf("number of right answer(s) : %d\ttotal score: %d\n", score, score * 10);164 }165 166 else167 {168 printf("End System\n");169 }170 171 return 0;172 }
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