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Possible Duplicate:
Create a pointer to two-dimensional array
当我调用函数 func4() 和 func5() 时，出现以下错误:
func4() error: cannot convert ‘short int (*)[3]’ to ‘short int**’ for argument ‘1’ to ‘int func4(short int**)’| func5() error: cannot convert ‘short int (*)[3]’ to ‘short int**’ for argument ‘1’ to ‘int func5(short int**)’|
如何更正调用函数 func4() 和 func5() 时的错误？这是我的代码:
#include <cstdio>
int func1(short mat[][3]);
int func2(short (*mat)[3]);
int func3(short *mat);
int func4(short **mat);
int func5(short *mat[3]);
int main()
{
short mat[3][3],i,j;
for(i = 0 ; i < 3 ; i++)
for(j = 0 ; j < 3 ; j++)
{
mat[i][j] = i*10 + j;
}
printf(" Initialized data to: ");
for(i = 0 ; i < 3 ; i++)
{
printf("\n");
for(j = 0 ; j < 3 ; j++)
{
printf("%5.2d", mat[i][j]);
}
}
printf("\n");
func1(mat);
func2(mat);
func3(&mat[0][0]);
func4(mat); //error: cannot convert ‘short int (*)[3]’ to
//‘short int**’ for argument ‘1’ to ‘int func4(short int**)’|
func5(mat); //error: cannot convert ‘short int (*)[3]’ to
//‘short int**’ for argument ‘1’ to ‘int func5(short int**)’|
return 0;
}
/*
Method #1 (No tricks, just an array with empty first dimension)
===============================================================
You don't have to specify the first dimension!
*/
int func1(short mat[][3])
{
register short i, j;
printf(" Declare as matrix, explicitly specify second dimension: ");
for(i = 0 ; i < 3 ; i++)
{
printf("\n");
for(j = 0 ; j < 3 ; j++)
{
printf("%5.2d", mat[i][j]);
}
}
printf("\n");
return 0;
}
/*
Method #2 (pointer to array, second dimension is explicitly specified)
======================================================================
*/
int func2(short (*mat)[3])
{
register short i, j;
printf(" Declare as pointer to column, explicitly specify 2nd dim: ");
for(i = 0 ; i < 3 ; i++)
{
printf("\n");
for(j = 0 ; j < 3 ; j++)
{
printf("%5.2d", mat[i][j]);
}
}
printf("\n");
return 0;
}
/*
Method #3 (Using a single pointer, the array is "flattened")
============================================================
With this method you can create general-purpose routines.
The dimensions doesn't appear in any declaration, so you
can add them to the formal argument list.
The manual array indexing will probably slow down execution.
*/
int func3(short *mat)
{
register short i, j;
printf(" Declare as single-pointer, manual offset computation: ");
for(i = 0 ; i < 3 ; i++)
{
printf("\n");
for(j = 0 ; j < 3 ; j++)
{
printf("%5.2d", *(mat + 3*i + j));
}
}
printf("\n");
return 0;
}
/*
Method #4 (double pointer, using an auxiliary array of pointers)
================================================================
With this method you can create general-purpose routines,
if you allocate "index" at run-time.
Add the dimensions to the formal argument list.
*/
int func4(short **mat)
{
short i, j, *index[3];
for (i = 0 ; i < 3 ; i++)
index[i] = (short *)mat + 3*i;
printf(" Declare as double-pointer, use auxiliary pointer array: ");
for(i = 0 ; i < 3 ; i++)
{
printf("\n");
for(j = 0 ; j < 3 ; j++)
{
printf("%5.2d", index[i][j]);
}
}
printf("\n");
return 0;
}
/*
Method #5 (single pointer, using an auxiliary array of pointers)
================================================================
*/
int func5(short *mat[3])
{
short i, j, *index[3];
for (i = 0 ; i < 3 ; i++)
index[i] = (short *)mat + 3*i;
printf(" Declare as single-pointer, use auxiliary pointer array: ");
for(i = 0 ; i < 3 ; i++)
{
printf("\n");
for(j = 0 ; j < 3 ; j++)
{
printf("%5.2d", index[i][j]);
}
}
printf("\n");
return 0;
}