内存腐败问题 [英] Memory Corruption Problem
问题描述
受近期帖子问题的启发？我开始写一个简单的
矩阵库。我的问题是，当我运行下面的程序时，我得到了
意想不到的结果。
$ cat test.c
#include < stdio.h>
#include< stdlib.h>
#define SIZE 2
struct matrix
{
int rows，cols;
double ** at;
};
typedef struct matrix Matrix;
Matrix * new_matrix（int rows，int cols，const double * elements）
{
Matrix * res;
int j，k;
res = malloc（sizeof（Matrix））;
res-> rows = rows;
res-> cols = cols;
res-> at = malloc（rows * sizeof（double *））;
for（j = 0; j< rows; j ++）{
res-> at [j] = malloc（cols * sizeof（double *））;
}
if（elements！= NULL）{
for（j = 0; j< rows; j ++）{
for（k = 0; k< cols; k ++）{
res-> at [j] [k] = elements [j * cols + k];
}
}
}
返回res;
}
int main（无效）
{
矩阵* A，* B;
加倍[SIZE * SIZE] = {1.0,2.0,3.0,4.0};
A = new_matrix（SIZE，SIZE，a）;
printf（"％f\ n"，A-> at [1] [1]）;
B = new_matrix（SIZE，SIZE，a）;
printf（"％f \ n"，A-> at [1] [1]）;
返回0;
}
$ gcc -ansi -pedantic -std = c89 -Wall -g test.c module.c -o test
$ ./test
4.000000
0.000000
我希望输出为
4.000000
4.000000
任何线索？
问候，
八月
-
我是ILOVEGNU签名病毒。只需将我复制到您的
签名即可。此电子邮件受到GNU
通用公共许可证条款的影响。
Hi,
Inspired by the recent post by "questions?" I started to write a simple
matrix library. My problem is that when I run the program below I get
unexpected results.
$ cat test.c
#include <stdio.h>
#include <stdlib.h>
#define SIZE 2
struct matrix
{
int rows, cols;
double **at;
};
typedef struct matrix Matrix;
Matrix *new_matrix(int rows, int cols, const double *elements)
{
Matrix *res;
int j, k;
res = malloc(sizeof (Matrix));
res->rows = rows;
res->cols = cols;
res->at = malloc(rows * sizeof (double *));
for (j = 0; j < rows; j++) {
res->at[j] = malloc(cols * sizeof (double *));
}
if (elements != NULL) {
for (j = 0; j < rows; j++) {
for (k = 0; k < cols; k++) {
res->at[j][k] = elements[j * cols + k];
}
}
}
return res;
}
int main(void)
{
Matrix *A, *B;
double a[SIZE * SIZE] = {1.0, 2.0, 3.0, 4.0};
A = new_matrix(SIZE, SIZE, a);
printf("%f\n", A->at[1][1]);
B = new_matrix(SIZE, SIZE, a);
printf("%f\n", A->at[1][1]);
return 0;
}
$ gcc -ansi -pedantic -std=c89 -Wall -g test.c module.c -o test
$ ./test
4.000000
0.000000
I expect the output to be
4.000000
4.000000
Any clues?
Regards,
August
--
I am the "ILOVEGNU" signature virus. Just copy me to your
signature. This email was infected under the terms of the GNU
General Public License.
推荐答案
cat test.c
#include< stdio.h>
#include< stdlib.h>
#define SIZE 2
< br $>
struct matrix
{
int rows，cols;
double ** at;
};
typedef struct matrix Matrix;
Matrix * new_matrix（int rows，int cols，const double * elements）
{
Matrix * res;
int j，k;
res = malloc（sizeof（Matrix））;
res-> rows = rows;
res-> cols = cols;
res-> at = malloc（rows * sizeof（double *））;
for（j = 0; j< rows; j ++）{
res-> at [j] = malloc（cols * sizeof（double *））;
}
if（elements！= NULL）{
for（j = 0; j< rows ; j ++）{
for（k = 0; k< cols; k ++）{
res-> at [j] [k] = elements [j * cols + k];
}
}
}
返回res;
}
int main（无效）
{
矩阵* A，* B;
双倍a [SIZE * SIZE] = {1.0,2.0,3.0,4.0};
A = new_matrix（SIZE，SIZE，a）;
printf（" ;％f \ n"，A-> at [1] [1]）;
B = new_matrix（SIZE，SIZE，a）;
printf（ "％f\ n，A-> at [1] [1]）;
返回0;
}
cat test.c
#include <stdio.h>
#include <stdlib.h>
#define SIZE 2
struct matrix
{
int rows, cols;
double **at;
};
typedef struct matrix Matrix;
Matrix *new_matrix(int rows, int cols, const double *elements)
{
Matrix *res;
int j, k;
res = malloc(sizeof (Matrix));
res->rows = rows;
res->cols = cols;
res->at = malloc(rows * sizeof (double *));
for (j = 0; j < rows; j++) {
res->at[j] = malloc(cols * sizeof (double *));
}
if (elements != NULL) {
for (j = 0; j < rows; j++) {
for (k = 0; k < cols; k++) {
res->at[j][k] = elements[j * cols + k];
}
}
}
return res;
}
int main(void)
{
Matrix *A, *B;
double a[SIZE * SIZE] = {1.0, 2.0, 3.0, 4.0};
A = new_matrix(SIZE, SIZE, a);
printf("%f\n", A->at[1][1]);
B = new_matrix(SIZE, SIZE, a);
printf("%f\n", A->at[1][1]);
return 0;
}
gcc -ansi -pedantic -std = c89 -Wall -g test.c module.c -o test
gcc -ansi -pedantic -std=c89 -Wall -g test.c module.c -o test
./ test
4.000000
0.000000
我希望输出为
4.000000
4.000000
任何线索？
问候，
八月
-
我是ILOVEGNU签名病毒。只需将我复制到您的
签名即可。此电子邮件受到GNU
通用公共许可证条款的影响。
./test
4.000000
0.000000
I expect the output to be
4.000000
4.000000
Any clues?
Regards,
August
--
I am the "ILOVEGNU" signature virus. Just copy me to your
signature. This email was infected under the terms of the GNU
General Public License.
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