problem with fwrite and fread, help please

[elisa]

Dear all,

I have problems in writeing and reading a block of data (long array) with fread and fwrite. If I write and read an integer array, everything looks fine, but when I try long array, sth strange happen, the data read from a file is not the same the data I supposed to write. Since I can't view the binary data file, I don't know what's wrong.

Here is my code, please help me, Thanks a lot!

Elisa

#include <stdio.h>
#define CHANNELS 2
#define SAMPLES 3


void main()
{
FILE *fp_out, *fp_in;
short row, column;
char filename[] = "datain_test.da t";
long datain[CHANNELS][SAMPLES] =
{111111111,2222 22222,33333333,
44444444,555555 5,6666666};
//size_t object_size = sizeof(long);
//size_t object_count = CHANNELS*SAMPLE S;
size_t op_return;


printf("Initial values of array: \n");
for(row = 0; row<CHANNELS; row++)
{
for (column =0; column <SAMPLES; column++)
{
printf("%ld ", datain[row][column]);
}
printf("\n");
}

fp_out = fopen(filename, "w");

op_return = fwrite(&datain, sizeof(datain[0][0]),sizeof(datain )/sizeof(datain[0][0]),fp_out);
printf("fwrite return code = %d\n", op_return);

fclose(fp_out);

fp_in = fopen(filename, "r");

op_return = fread(&datain,s izeof(datain[0][0]),sizeof(datain )/sizeof(datain[0][0]),fp_in);
printf("read values of array from file: \n");

for(row = 0; row<CHANNELS; row++)
{
for (column =0; column <SAMPLES; column++)
{
printf("%ld ", datain[row][column]);
}
printf("\n");
}
printf("fread return code = %d\n",op_return );


fclose(fp_in);
asm(" nop");
}

and here is the output:

Initial values of array:
111111111 222222222 33333333
44444444 5555555 6666666
fwrite return code = 6
read values of array from file:
10420423 4063374 16515157
10879004 5505123 6619306
fread return code = 6

[elisa]

I figured it out. Since I use TI C55xx DSP, so fread can only read a byte each time. More details in TI's webpage:

http://focus.ti.com/mcu/docs/mcusupporttechd ocsc.tsp?sectio nId=96&tabId=15 02&abstractName =spra757
Dear all,

I have problems in writeing and reading a block of data (long array) with fread and fwrite. If I write and read an integer array, everything looks fine, but when I try long array, sth strange happen, the data read from a file is not the same the data I supposed to write. Since I can't view the binary data file, I don't know what's wrong.

Here is my code, please help me, Thanks a lot!

Elisa

#include <stdio.h>
#define CHANNELS 2
#define SAMPLES 3


void main()
{
FILE *fp_out, *fp_in;
short row, column;
char filename[] = "datain_test.da t";
long datain[CHANNELS][SAMPLES] =
{111111111,2222 22222,33333333,
44444444,555555 5,6666666};
//size_t object_size = sizeof(long);
//size_t object_count = CHANNELS*SAMPLE S;
size_t op_return;


printf("Initial values of array: \n");
for(row = 0; row<CHANNELS; row++)
{
for (column =0; column <SAMPLES; column++)
{
printf("%ld ", datain[row][column]);
}
printf("\n");
}

fp_out = fopen(filename, "w");

op_return = fwrite(&datain, sizeof(datain[0][0]),sizeof(datain )/sizeof(datain[0][0]),fp_out);
printf("fwrite return code = %d\n", op_return);

fclose(fp_out);

fp_in = fopen(filename, "r");

op_return = fread(&datain,s izeof(datain[0][0]),sizeof(datain )/sizeof(datain[0][0]),fp_in);
printf("read values of array from file: \n");

for(row = 0; row<CHANNELS; row++)
{
for (column =0; column <SAMPLES; column++)
{
printf("%ld ", datain[row][column]);
}
printf("\n");
}
printf("fread return code = %d\n",op_return );


fclose(fp_in);
asm(" nop");
}

and here is the output:

Initial values of array:
111111111 222222222 33333333
44444444 5555555 6666666
fwrite return code = 6
read values of array from file:
10420423 4063374 16515157
10879004 5505123 6619306
fread return code = 6[/quote]

[horace1]

try opening your files in binary mode wite and read
e.g.

fp_out = fopen(filename,"wb");
 and
 
fp_in = fopen(filename,"rb");