Question

使用一个小型控制台应用程序，该应用程序对类似维度的矩阵的值执行数学运算。 CreateMatrix（）函数返回int **，它给出了数组的维度，现在我正在尝试接受输入并遇到错误。我之前从未使用过malloc，所以我认为我使用的是错误的东西。我会尝试省略您在查找问题时不需要的任何代码。

    int rowInput, colInput;
    int** customA, customB;

    int main(void) {
        printf("\nEnter the number of Rows: ");
        scanf(" %i", &rowInput);
        printf("\nEnter the number of Columns: ");
        scanf(" %i", &colInput);
        customA = CreateMatrix(colInput, rowInput);
        for (int row = 0; row <= rowInput; row++) {
          for (int column = 0; column <= colInput; column++) {
            printf("Enter input for value at MatrixA[%d][%d]\n", row, column);
            scanf(" %i", &customA[row][column]);
          }
        }
        PrintMatrix(rowInput, colInput, customA);
        printf(" \n");
      }
    }

CreateMatrix（）和includes，在我的Header.h中声明

#include <stdio.h>
#include <stdlib.h>
#define Row 2
#define Col 5
#define Max 10

/**
*Dynamically allocate memory for custom matrix based on desired dimensions input
*@return int** to newly allocated matrix
**/
int** CreateMatrix(int colInput, int rowInput);

/**
*Checks input for matrix Row and columns exceeding maximum allowed
*
*/
int CheckMaximums(int *rowInput, int *colInput);

CreateMatrix（）在我的CLibrary.c中定义，我在CMake中链接。包含CheckMaximums（）仅供您参考，因为它在CreateMatrix中使用。不过，我对这个逻辑没有任何问题。

#include <Header.h>

int** CreateMatrix(int colInput, int rowInput) {
  int** customMatrix;
  CheckMaximums(&rowInput, &colInput);
  printf(" \n");
  customMatrix = (int**)malloc(rowInput);
  for (int i = 0; i < colInput; i++)
    customMatrix = (int*)malloc(colInput);
  return customMatrix;
}

int CheckMaximums(int *rowInput, int *colInput) {
  if (*rowInput > Max || *colInput > Max) {
    if (*rowInput > Max && *colInput > Max) {
      *rowInput = Max;
      *colInput = Max;
      printf("\nYour Row and Column sizes both exceed the maximum allowed values\n"
             "Row size has been set to max value (10)\n"
             "Column size has been set to max value (10)");
    } 
    else if (*rowInput > Max) {
      *rowInput = Max;
      printf("\nYour Row size exceeds the maximum allowed value\n"
             "Row size has been set to max value (10)\n");
    }
    else {
      *colInput = Max;
      printf("\nYour Column size exceeds the maximum allowed value\n"
             "Column size has been set to max value (10)\n");
    }
  }
}

在此先感谢，我知道这很重要，试着将其减少到最低限度！

Answer 1

在CreateMatirx中，

malloc需要知道要分配的总字节数。将每个元素的大小所需的元素数乘以。

customMatrix = malloc(rowInput * sizeof ( int*);//each element is a pointer to int
for (int i = 0; i < rowInput; i++)
    customMatrix[i] = malloc(colInput * sizeof int);//each element is an int

第一个malloc为rowInput指针分配足够的内存。可以像索引customMatrix[0]到customMatrix[rowInput - 1]的数组一样访问每个指针 for循环遍历每个指针并为colInput整数分配足够的内存。

在main中，将＆lt; =更改为＆lt;在for循环中，否则你访问超出分配的内存

for (int row = 0; row < rowInput; row++) {
    for (int column = 0; column < colInput; column++) {

应该检查malloc和scanf的返回，因为这些函数可能会失败

在动态分配的矩阵中输入值 - C.

1 个答案: