如何找到最小值？

Question

我需要让用户输入 7 到 12 ([7;12]) 之间的 N（数字）。然后，我需要让用户输入数字的数量，应该等于N。然后，我需要输出这些数字的总和，找到平均值，最小值和最大值。 它工作得很好，除了最低限度。当数字从 1 开始计数时，我的程序显示最小值为 0。谢谢你...

#include <stdio.h>

int main(void) {
  int i = 0;
  int N;
  float numbers;
  float sum = 0;
  float average, min, max;

  printf("Choose a number between 7 and 12: ");
  scanf("%d", &N);

  if (N >= 7 && N <= 12) {
    printf("You have chosen: %d\n", N);
    printf("Now choose the amount of N numbers you have chosen: ");

    for (i = 0; i < N; i++) {
      numbers = N; // the numbers the user enters must be
                   // strictly == N
      scanf("%f", &numbers);
      sum = sum + numbers;
      average = sum / numbers;

      if (numbers < min) {
        min = numbers;
      }

      if (numbers > max) {
        max = numbers;
      }
    }

    printf("The sum of your numbers is: %f\n The average of "
           "numbers: %f\n The max: %f\n The min: %f\n",
           sum, average, max, min);
  }
}

输出是：

    Choose a number between 7 and 12: 7                                                                                           
You have chosen: 7                                                                                                            
Now choose the amount of N numbers you have chosen: 1                                                                         
2                                                                                                                             
3                                                                                                                             
4                                                                                                                             
5                                                                                                                             
6                                                                                                                             
7                                                                                                                             
The sum of your numbers is: 28.000000                                                                                         
 The average of numbers: 4.000000                                                                                             
 The max: 7.000000                                                                                                            
 The min: 0.000000 

Answer 1

您的min 和max 值未初始化使用。在您的平台/编译器上，似乎这些默认初始化为零，但 C 标准不要求这样做。

要解决此问题，只需将这些变量（在它们声明时）初始化为不能成为最终值的值（如 FLT_MAX 常量的 +/- 值，在 <float.h> 中定义）：

    //...
    float average, min = FLT_MAX, max = -FLT_MAX;
    //...

Answer 2

我会以完全不同的方式来解决这个问题。将数字存储在数组中，然后对其进行排序。这是一个使用整数的示例，但很容易修改为浮点使用。

#include <stdio.h>

// Bubble sort
void bubbleSort (int *numArray, int numElements) {
    int sorted = 0, temp;
    while (!sorted) {
        // Set this flag here
        sorted = 1;
        for (int i = 0; i < numElements - 1; i++) {
            // Swaps the numbers
            if (numArray [i] > numArray [i + 1]) {
                temp = numArray [i];
                numArray [i] = numArray [i + 1];
                numArray [i + 1] = temp;
                sorted = 0;
            }
        }
    }
}

float calcAverage (int numArray [], int numElements) {
  float avg = 0;
  for (int i = 0; i < numElements; i++) avg += numArray [i];

  return avg / numElements;
}

int main() {
    int numElements = 0;
    // Ensure they actually enter a number!
    while (numElements < 7 || numElements > 12) {
        printf ("Please enter a number between 7 and 12: ");
        // Input validation is always important in my opinion.
        if (!scanf ("%d", &numElements)) {
            printf ("ERROR: NaN value passed! ");
        }
        else if (numElements < 7 || numElements > 12) printf ("ERROR: Invalid number! ");
        // Clear the buffer
        while (getchar() != '\n');
    }

    printf ("You have chosen: %d.\n", numElements);
    
    // Create our array and store our current number.
    int numArray [numElements], fGood;

    for (int i = 0; i < numElements; i++) {
      // Reset this flag at the beginning of the loop
      fGood = 0;

      while (!fGood) {
        printf ("Please enter value %d: ", i + 1);
        // Assume it's a good value
        fGood = 1;

        if (!scanf ("%d", &numArray [i])) {
          printf ("ERROR: Invalid value passed! ");
        }
        while (getchar() != '\n');
      }
    }

    bubbleSort (numArray, numElements);
    printf ("Average of entered numbers: %.2f\nMinimum value: %d\nMaximum value: %d\n", calcAverage(numArray, numElements), numArray [0], numArray [numElements - 1]);

    return 0;
}