感谢我之前在这里得到的所有帮助。
在下面的程序中,我想创建一个随机矩阵,将其打印到屏幕上,将其写入文件,然后从文件中扫描该矩阵的副本并将副本打印到屏幕上,一切正常,除了何时我尝试从文件中读取,我认为我的代码中的算法不正确,
scanf 函数失败我不知道为什么....
double *matrix_read(FILE *fptr, double *mat, int m, int n ) ;
double *matrix_read(FILE *fptr,double *mat, int m, int n ) {
int i,j;
double *ptr,x ;
ptr=mat;
if((fptr=fopen("matrixA.txt","r"))==NULL)
{
puts("Cannot Open File");
}
rewind(fptr);
fscanf( fptr,"\n\nrows %d, columns %d\n\n", &m, &n) ;
mat = (double *) malloc( sizeof( double ) * m * n ) ;
for ( i=0; i < m; i++ )
{
for ( j=0; j < n; j++ )
{
fscanf(fptr, " %5.2lf", &x );
*ptr++=x;
}
}
fclose(fptr);
return mat ;
}
在我的main
中,函数调用如下:
rand_matrix(MATRIX.matrix, MATRIX.rows, MATRIX.cols ); /* populates matrix with random data */
print_matrix(MATRIX.matrix, MATRIX.rows, MATRIX.cols ) ; /* prints the matrix */
matrix_write( fptr, MATRIX.matrix, MATRIX.rows, MATRIX.cols ) ; /* writes matrix to file*/
_flushall();
getchar();
MATRIX1.matrix=matrix_read( fptr, MATRIX.matrix, MATRIX.rows, MATRIX.cols ) ; /* reads above matrix from file as a copy */
print_matrix(MATRIX1.matrix, MATRIX.rows, MATRIX.cols ) ; /* prints this copyed matrix*/
当打印复制的矩阵时,我得到一堆乱码,大量数字(即 1259000000000000000000)我认为这些是内存位置名称或其他东西,有人可以帮我修复我的 read_matrix()
函数吗?
非常感谢。
下面是我的完整代码(编译)。
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <malloc.h>
#include <conio.h>
double random() ;
double *rand_matrix( double *mat, int m, int n ) ;
void print_matrix( double *mat, int m, int n ) ;
void matrix_write(FILE *fptr, double *mat, int m, int n ) ;
double *matrix_read(FILE *fptr, double *mat, int m, int n ) ;
int main()
{
struct matrep {
unsigned rows,cols;
double *matrix;
} MATRIX,MATRIX1,MATRIX2;
int check = 0 ;
FILE *fptr;
printf( "\n\nMatrix Manipulations Program" );
do {
printf( "\n\nEnter matrix dimensions : rows x columns : " );
check = scanf( "%d x %d", &MATRIX.rows, &MATRIX.cols );
_flushall();
} while ( check != 2 || MATRIX.rows < 1 || MATRIX.cols < 1 ) ;
MATRIX.matrix = (double *) malloc( sizeof( double ) * MATRIX.rows * MATRIX.cols ) ;
if ( !MATRIX.matrix ){
printf( "\n\nSTOP : unable to allocate memory - exiting program") ;
exit( 1 ) ;
}
rand_matrix(MATRIX.matrix, MATRIX.rows, MATRIX.cols ); /* populates matrix with random data */
print_matrix(MATRIX.matrix, MATRIX.rows, MATRIX.cols ) ; /* prints the matrix */
matrix_write( fptr, MATRIX.matrix, MATRIX.rows, MATRIX.cols ) ; /* writes matrix to file*/
_flushall();
getchar();
MATRIX1.matrix=matrix_read( fptr, MATRIX.matrix, MATRIX.rows, MATRIX.cols ) ; /* reads above matrix from file as a copy */
print_matrix(MATRIX1.matrix, MATRIX.rows, MATRIX.cols ) ; /* prints this copyed matrix*/
_flushall();
getchar();
}
/***********************************************************/
double random()
{
static int seeded = 0;
double val ;
if ( !seeded )
{
srand( time(NULL) ) ;
seeded = 1;
}
val = ((double)rand())/ (double)RAND_MAX * 100.0 ;
return val ;
}
/***********************************************************/
double *rand_matrix( double *mat, int m, int n )
{
double *ptr ;
int i, j ;
ptr = mat ;
for ( i=0; i < m; i++ ){
for ( j=0; j < n; j++ ){
*ptr++ = random() ;
}
}
return mat ;
}
/***********************************************************/
void print_matrix( double *mat, int m, int n )
{
double *ptr ;
int i, j ;
if ( mat==0 || m==0 || n==0 )
{
printf("\n\nEmpty matrix" );
return ;
}
ptr = mat ;
printf( "\n\nrows %d, columns %d\n\n", m, n) ;
for ( i=0; i < m; i++ )
{
for ( j=0; j < n; j++ )
{
printf( "\t%5.2lf", *ptr++ );
}
printf( "\n" ) ;
}
}
/***********************************************************/
void matrix_write(FILE *fptr,double *mat, int m, int n ) {
int i,j;
if((fptr=fopen("matrixA.txt","w"))==NULL)
{
puts("Cannot Open File");
}
fprintf( fptr,"\n\nrows %d, columns %d\n\n", m, n) ;
for ( i=0; i < m; i++ )
{
for ( j=0; j < n; j++ )
{
fprintf(fptr, " %5.2lf", *mat++ );
}
fprintf(fptr, "\n" ) ;
}
fclose(fptr);
}
/***********************************************************/
double *matrix_read(FILE *fptr,double *mat, int m, int n ) {
int i,j;
double *ptr,x ;
ptr=mat;
if((fptr=fopen("matrixA.txt","r"))==NULL)
{
puts("Cannot Open File");
}
rewind(fptr);
fscanf( fptr,"\n\nrows %d, columns %d\n\n", &m, &n) ;
mat = (double *) malloc( sizeof( double ) * m * n ) ;
for ( i=0; i < m; i++ )
{
for ( j=0; j < n; j++ )
{
fscanf(fptr, " %5.2lf", &x );
*pt++r=x;
}
}
fclose(fptr);
return mat ;
}
最佳答案
for ( i=0; i < m; i++ )
{
for ( j=0; j < n; j++ )
{
fscanf(fptr, " %5.2lf", &x );
*ptr=x;
}
}
虽然您的整个代码太长而无法阅读,但此部分肯定是错误的。您必须在某个时间递增指针,否则只会初始化第一个元素。尝试:
*ptr++ = x;
valgrind
是检测此类错误的好工具,当您访问(或打印,在您的情况下)未初始化的内存时,它会抛出错误。
关于C 将随机矩阵写入文件,然后使用格式化 I/O 从文件中读取和复制所述矩阵,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8659426/