Sheldon写道：

/ *将数据写入文件* /

if（ROW * COL！= fwrite（tmp，sizeof *） tmp，COL，fp））/ *用fwrite（a，b，c）检查字节

文件大小* /

，d）如果写完所有数据，则返回c。不是
b * c。


顺便说一句，Perl和Python之类的许多函数都来自

标准C.


Tom

Tom St Denis skrev：

Sheldon写道：

/ *将数据写入文件* /

if（ROW * COL！ = fwrite（tmp，sizeof * tmp，COL，fp））/ *检查字节

文件大小* /

with fwrite（a，b，c，d）如果写入了所有数据，则返回c。不是
b * c。


顺便说一句，Perl和Python之类的许多函数都来自

标准C.


Tom

我同意有很多相似之处，但我告诉你写（）

python并不像老生常谈。我尝试了以下变体：

if（ROW * COL！= fwrite（tmp，sizeof * tmp，ROW * COL，fp））


但是这会导致分段错误。

Sheldon写道：

我同意有很多相似之处，但我告诉你写（）在

python并不是一个问题。我尝试了以下变体：

if（ROW * COL！= fwrite（tmp，sizeof * tmp，ROW * COL，fp））


但是这会导致分段错误。

您是否考虑过阅读fwrite的联机帮助页？


BTW glibc也为C写了write（） 。如果你更熟悉

写（）使用它。


Tom

Hi,

I am trying to learn C from scratch and, though I do know how to
program in Python, many things in C are hard to understand - even
after reading the examples. I guess because so many variations exists.
Can someone explain why this variation of fwrite fails:

#include <stdio.h>
#include <stdlib.h>
#define ROW 15 /* In order to have more memory and no segmentation
faults, request more memory */
#define COL 15
#define FILENAME "/data/aux/test_array.dat"

double tmp[ROW][COL];
int main(void)
{
FILE *fp; /* declare a file pointer */
int i, j, data;
float count;
printf("Rows -%d\tCol -%d\n",ROW, COL);
/* Assigning data to the array */
count = 2.0;
for(i = 0; i < ROW; i++)
{
for(j = 0; j < COL; j++)
{
tmp[i][j] = count;
count++;
/* printf("%f\n",count); */
}
}
printf("Finished writing to array\n");
printf("Opening file: %s\n",FILENAME);
if ((fp = fopen(FILENAME, "wb")) == NULL)
{
fprintf(stderr, "Error opening file %s in read mode.\n",
FILENAME);
fclose(fp);
return EXIT_FAILURE;
}
else
printf("File opened successfully.\n\n");
/* Write data to file */
if(ROW*COL != fwrite(tmp, sizeof *tmp, COL, fp)) /* Checking the byte
size of the file */
{
fprintf(stderr, "Error writing to file.\n");
fclose(fp);
return EXIT_FAILURE;
}
fclose(fp);
/* done writing to file */
return 0;
}
Thanks in advance!
Sheldon

Sheldon wrote:

/* Write data to file */
if(ROW*COL != fwrite(tmp, sizeof *tmp, COL, fp)) /* Checking the byte
size of the file */

with fwrite(a, b, c, d) it returns c if it wrote all the data. Not
b*c.

btw, many functions in things like Perl and Python are borrowed from
standard C.

Tom

Tom St Denis skrev:

Sheldon wrote:

/* Write data to file */
if(ROW*COL != fwrite(tmp, sizeof *tmp, COL, fp)) /* Checking the byte
size of the file */

with fwrite(a, b, c, d) it returns c if it wrote all the data. Not
b*c.

btw, many functions in things like Perl and Python are borrowed from
standard C.

Tom

I agree that there are many similarities but I tell you write() in
python is not as criptic. I have tried that variation of:
if(ROW*COL != fwrite(tmp, sizeof *tmp, ROW*COL, fp))

But this causes a segmentation fault.

Sheldon wrote:

I agree that there are many similarities but I tell you write() in
python is not as criptic. I have tried that variation of:
if(ROW*COL != fwrite(tmp, sizeof *tmp, ROW*COL, fp))

But this causes a segmentation fault.

Have you given any thought to reading the manpage for fwrite?

BTW glibc has write() for C as well. If you are more familiar with
write() use that.

Tom