随机数（加法游戏）问题

Question

我正在为我的 C class 入门制作一个 addition/multiplication 游戏。该程序的 objective 是询问用户，您想要使用的最大数量是多少，它将在该最大范围内播种随机数，以及您想要做多少不同的问题。当我运行程序并进行数学计算时，它告诉我总和不正确，并提供了一个不正确的答案，通常是一个很大的数字，如“1254323”。你能指出我做错了什么的正确方向吗？

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

int main() {

    int maxNumber, num1, num2, sum, answer, problems, i;

    srand(time(NULL));

    //printf("Would you like 1)Addition or 2)Multiplication?\n")
    printf("Enter your Max Number:");
    scanf("%d", &maxNumber);

    printf("How many problems do you want?\n");
    scanf("%d", &problems);

    sum = num1 + num2;

    while(i != problems) {
        num1 = rand()%maxNumber;
        num2 = rand()%maxNumber;
        i++;

        printf("What is %d + %d\n",num1, num2);
        scanf("%d", &answer);

        if(answer != sum){
            printf("Sorry, that's incorrect, the answer is %d\n", sum);
        }

        else{
            printf("Correct!\n");
        }
    }

    return 0;
}

Answer 1

您在设置 num1 和 num2 之前分配 sum。

将 sum = num1 + num2; 行移动到 num2 = rand()%maxNumber; 行之后的循环中，它应该可以正常工作。

还有一些其他错误（例如用 0 初始化 i）。

顺便说一句，通常认为使用 for 循环而不是 while 循环是更好的做法。

这里是更易读的代码

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

int main(){
  int maxNumber, num1, num2, sum, answer, problems, i;
  srand(time(NULL));

  printf("Enter your Max Number:");
  scanf("%d", &maxNumber);

  printf("How many problems do you want?\n");
  scanf("%d", &problems);

  for (i = 0; i < problems; i++) {
    num1 = rand()%maxNumber;
    num2 = rand()%maxNumber;
    sum = num1 + num2;

    printf("What is %d + %d\n",num1, num2);
    scanf("%d", &answer);

    if(answer != sum){
      printf("Sorry, that's incorrect, the answer is %d\n", sum);
    } else {
      printf("Correct!\n");
    }
  }

  return 0;
}

Answer 2

您在使用变量时未对其进行初始化。变化：

int maxNumber, num1, num2, sum, answer, problems, i;

收件人：

int maxNumber = 0, num1 = 0, num2 = 0, sum = 0, answer = 0, problems = 0, i = 0;

此外，将 sum = num1 + num2; 行移动到创建 num1 和 num2 的位置之后。

Answer 3

您的程序存在多个问题，包括格式问题。以下是更正：

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

int main(){
    int maxNumber, num1, num2, sum, answer, problems, i;

    srand(time(NULL));

    //printf("Would you like 1)Addition or 2)Multiplication?\n")
    printf("Enter your Max Number:");
    scanf("%d", &maxNumber);

    printf("How many problems do you want?\n");
    scanf("%d", &problems);

    // issue: i was not initialized
    i = 0;
    while(i != problems){
        i++;
        num1 = rand()%maxNumber;
        num2 = rand()%maxNumber;

        printf("What is %d + %d\n", num1, num2);
        // issue: sum was not calculated here
        sum = num1 + num2;
        scanf("%d", &answer);

        if(answer != sum){
            printf("Sorry, that's incorrect, the answer is %d\n", sum);
        }
        else{
            printf("Correct!\n");
        }
    }
    return 0;
}

Answer 4

您定义 sum = num1 + num2，其中 num1 和 num2 根本没有赋值。默认情况下，C 不会将数字初始化为零。这就是为什么你有这么大的数字。

只需在 num2 = rand()%maxNumber; 之后添加 sum = num1 + num2，一切正常！

随机数（加法游戏）问题

Random Number (addition game) issue

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