使用C在内存中实现二维数组

Question

实际问题 - 在矩阵中找到鞍点。

我的函数调用 - find_saddle_point((Arr,rows);

我的函数原型 - void find_saddle_point(int *,int);

初始化 -

int rows , column ;

int Arr[rows][column];

警告- 警告：从不兼容的指针类型

传递“find_saddle_point”的参数 1

我的临时解决方案 - find_saddle_point(((int *)Arr,rows);

Answer 1

You declared a two dimensional array.

int Arr[rows][column];

Used in expressions like in this function call

find_saddle_point((Arr,rows);

it is implicitly converted to pointer to its first element and has the type int ( * )[column].

However the corresponding parameter has the type int * and there is no implicit conversion from the type int ( * )[column] to the type int *.

void find_saddle_point(int *,int);

So the compiler issues an error.

As for your temporary "solution"

find_saddle_point(((int *)Arr,rows);

then it can result in undefined behavior.

Declare the function like

void find_saddle_point( int, int, int [][*]);

In its definition you shall specify the names of parameters.

void find_saddle_point( int row, int column, int [][column])
{
    // ...
}

Also for dimensions of arrays it is better to use the type size_t instead of the type int.

Here is a demonstrative program.

#include <stdio.h>

void find_saddle_point( size_t, size_t, int a[][*] );

void fill( size_t rows, size_t cols, int a[][cols] )
{
    for ( size_t i = 0; i < rows; i++ )
    {
        for ( size_t j = 0; j < cols; j++ )
        {
            a[i][j] = i * cols + j;
        }
    }
}

int main(void) 
{
    size_t rows = 3;
    size_t cols = 5;

    int a[rows][cols];

    fill( rows, cols, a );

    for ( size_t i = 0; i < rows; i++ )
    {
        for ( size_t j = 0; j < cols; j++ )
        {
            printf( "%2d ", a[i][j] );
        }
        putchar( '\n' );
    }

    return 0;
}

Its output is

 0  1  2  3  4 
 5  6  7  8  9 
10 11 12 13 14

Of course the first function declaration in this simple program is redundant and shown only to demonstrate how a function with a parameter that has a type of a variable-length array can be declared.

使用C在内存中实现二维数组

Implementaion of 2-D array in meomory using C

c

parameters

multidimensional-array

implicit-conversion

variable-length-array