找到数组平均值的函数

Question

我是否正确实施了float overallavg(float* matrix, int rows, int cols)？我想我没有。我试图返回矩阵指向的数组元素的平均值。我应该将其他两个函数调用到整个函数中，然后除以数组中的总数元素吗？

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

float *readMatrix(int rows, int cols);
float *rowavg(float *matrix, int rows, int cols);
float *colavg(float *matrix, int rows, int cols);
float overallavg(float* matrix, int rows, int cols);
void printavg(float *matrix, float *rowAve, float *colAve, float overallAve, int rows, int cols);

#define MAX_DIM 10

int main(void)
{
  int done = 0;
  int rows, cols;
  float *dataMatrix;
  float *rowAveVector;
  float *colAveVector;
  float overallAve;

  while (!done)
  {
    // Prompt user to enter row and column dimensions of matrix (must be > 0)
    do
    {
        printf("Enter row dimension (must be between 1 and %d): ", MAX_DIM);
        scanf("%d", &rows);

    } while(rows <= 0 || rows > MAX_DIM);
    do
    {
        printf("Enter column dimension (must be between 1 and %d): ", MAX_DIM);
        scanf("%d", &cols);
    } while(cols <= 0 || cols > MAX_DIM);

    dataMatrix = readMatrix(rows, cols);
    if (dataMatrix == NULL)
    {
        printf ("Program terminated due to dynamic memory allocation failure\n");
        return (0);
    }


    rowAveVector = rowAverage(dataMatrix, rows, cols);
    colAveVector = colAverage(dataMatrix, rows, cols);
    if(rowAveVector == NULL || colAveVector == NULL)
    {
     printf("malloc failed.  Terminating program\n");
     return (0);
    }
    overallAve = overallAverage(dataMatrix, rows, cols);

    //Print Averages
    printAverages(dataMatrix, rowAveVector, colAveVector, overallAve, rows, cols);

    free(dataMatrix);
    free(rowAveVector);
    free(colAveVector);

    //Check if user wants to enter a new matrix
    printf("Enter 0 to continue with a new matrix\n");
    printf("Enter any other number to terminate the program: ");
    scanf("%d", &done);
  }
  //That's it, we are done
  return (0);
}

float *readMatrix(int rows, int cols)
{

    int i=0;
    int j=0;
    int elements=0;
    float *m=malloc(rows*cols*sizeof(float));
    if (m==NULL)
    {
        printf("error\n");
        return NULL;
    }
    printf("Enter values for the matrix: ");
    for (i=0;i<rows;i++)
    {
        for (j=0;j<cols;j++)
        {
            elements = i*cols+j;
            scanf("%f", &m[elements]);
        }
    }
    return m;
}

float *readMatrix(int rows, int cols)
{
    int i=0;
    int j=0;
    int elements=0;
    float *m=malloc(rows*cols*sizeof(float));
    if (m==NULL)
    {
        printf("error\n");
        return NULL;
    }
    printf("Enter values for the matrix: ");
    for (i=0;i<rows;i++)
    {
        for (j=0;j<cols;j++)
        {
            elements = i*cols+j;
            scanf("%f", &m[elements]);
        }
    }
    return m;
}


float *rowavg(float *matrix, int rows, int cols)
{
  if (matrix==NULL)
  {
      return NULL;
  }
  int i=0;
  int j=0;
  float mean=0;
  float *Average_array=malloc(rows*sizeof(float));
  if (Average_array==NULL)
  {
      return NULL;
  }
  for (i=0;i<rows;i++)
  {
      for (j=0;j<cols;j++)
      {
          mean+=matrix[i*cols+j];
      }
      Average_array[i]=(float)(mean/cols);
  }
  return Average_array;
}


float *colavg(float *matrix, int rows, int cols)
{
  if (matrix==NULL)
  {
      return NULL;
  }
  int i=0;
  int j=0;
  float mean=0;
  float *Average_array=malloc(cols*sizeof(float));
  if (Average_array==NULL)
  {
      return NULL;
  }
  for (i=0;i<cols;i++)
  {
      for (j=0;j<rows;j++)
      {
          mean+=matrix[j*cols+i];
      }
      Average_array[i]=(float)(mean/rows);
  }
  return Average_array;
}

float overallavg(float* matrix, int rows, int cols)
{
  if (matrix==NULL)
  {
      return NULL;
  }
  int i=0;
  int j=0;
  float mean_1=0;
  float mean_2=0;
  float avg=0;
  float elements=0;
  float sum=0;
  elements=rows*cols;
  for (i=0;i<rows;i++)
  {
      for (j=0;j<cols;j++)
      {
          mean_1+=matrix[i*rows+j];
      }
  }
  for (i=0;i<cols;i++)
  {
      for (j=0;j<rows;j++)
      {
          mean_2+=matrix[j*cols+i];
      }
  }
  sum=mean_1+mean_2;
  avg=sum/elements-1;
}

Answer 1

以下代码：

1. 干净地编译
2. 包含所需的#include语句

注意：这一行：

avg=sum/elements-1;

不会计算所有元素的平均值，而是计算一个稍大的值，因为元素的总数减少1

建议，在函数中：overallavg()不计算单独的'均值'值，而是简单地逐步遍历整个数组求和每个元素，然后除以元素总数

建议，使用4个空格的缩进宽度，因为即使使用可变宽度字体，也很容易看到。 2个带有可变宽度字体的空格看起来像缩进的行缩进约为字母宽度的1/2。 I.E.几乎看不见，看起来非常凌乱。 （代码被多次读取所以应该写得非常容易阅读。

#include <stdio.h> // printf() scanf()
#include <stdlib.h> // malloc, free()

float *readMatrix( size_t rows, size_t cols)
{
    //int i=0;
    //int j=0;
    size_t elements=0;

    float *m=malloc(rows*cols*sizeof(float));

    if (m==NULL)
    {
        printf("error\n");
        return NULL;
    }

    printf("Enter values for the matrix: ");

    for (size_t i=0; i<rows; i++)
    {
        for ( size_t j=0; j<cols; j++)
        {
            elements = i*cols+j;
            scanf("%f", &m[elements]);
        }
    }

    return m;
}


float *rowavg(float *matrix, size_t rows, size_t cols)
{
  if (matrix==NULL)
  {
      return NULL;
  }

  //int i=0;
  //int j=0;
  float mean=0;

  float *Average_array=malloc(rows*sizeof(float));

  if (Average_array==NULL)
  {
      return NULL;
  }

  for ( size_t i=0; i<rows; i++)
  {
      for ( size_t j=0; j<cols; j++)
      {
          mean+=matrix[i*cols+j];
      }
      Average_array[i] = (mean/(float)cols);
  }

  return Average_array;
}


float *colavg(float *matrix, size_t rows, size_t cols)
{
  if (matrix==NULL)
  {
      return NULL;
  }

  //int i=0;
  //int j=0;
  float mean=0;

  float *Average_array = malloc( cols*sizeof(float) );

  if (Average_array==NULL)
  {
      return NULL;
  }

  for ( size_t i=0; i<cols; i++)
  {
      for (size_t j=0; j<rows; j++)
      {
          mean+=matrix[j*cols+i];
      }
      Average_array[i] = (mean/(float)rows);
  }
  return Average_array;
}



float overallavg(float* matrix, size_t rows, size_t cols)
{
    #if 0
    if (matrix==NULL)
    {
      return NULL;
    }
    #endif

  //int i=0;
  //int j=0;
  float mean_1=0;
  float mean_2=0;
  float avg=0;
  float elements=0;
  float sum=0;

  elements= (float)rows* (float)cols;

  for ( size_t i=0;i<rows;i++)
  {
      for ( size_t j=0;j<cols;j++)
      {
          mean_1+=matrix[i*rows+j];
      }
  }

  for ( size_t i=0; i<cols; i++)
  {
      for ( size_t j=0; j<rows ;j++)
      {
          mean_2+=matrix[j*cols+i];
      }
  }

  sum=mean_1+mean_2;
  avg=sum/elements-1;

  return avg;
}