Hi all,
This c code I use it to compute the number of elements in file:
fseek(file, 0, SEEK_END);
size_t inSize = ftell(file);
size_t no_ofelem = inSize/2;
I converted it to work on Arduino ide in this way:
file.seek(file.size());
inSize = file.position();
no_ofelem = inSize/2;
But this gave me not the same result. Can you please tell me how can I use like ftell(file); with Arduino IDE ?
Please explain what you mean by an element of a file. Your code appears to print the number of bytes in a file divided by 2
Yes, the c code return the number of values in txt file. The type of value is (int16).
That relies on each value consisting of exactly one character, thus restricting the value to a range of 0 to 9 and there being no Linefeeds between values
An int will certainly consist of more than a single character
This is the C code:
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>
#include <stdint.h>
int16_t *readInt16(char *srcFilePath, size_t *nbEle)
{
size_t inSize;
FILE *pFile = fopen(srcFilePath, "rb");
if (pFile == NULL)
{
printf("Failed to open input file. 1\n");
return NULL;
}
fseek(pFile, 0, SEEK_END);
inSize = ftell(pFile);
printf("inSize = %d \n",inSize);
nbEle = inSize/2;
printf("no_ofelem = %d \n",nbEle);
fclose(pFile);
if(inSize<=0)
{
printf("Error: input file is wrong!\n");
}
int16_t *daBuf = (int16_t *)malloc(inSize);
pFile = fopen(srcFilePath, "rb");
if (pFile == NULL)
{
printf("Failed to open input file. 2\n");
return NULL;
}
fread(daBuf, 2, *no_ofelem, pFile);
fclose(pFile);
return daBuf;
}
void main(){
// put your setup code here, to run once:
size_t *no_ofelem ;
char srcFilePath[]="test_.txt";
int16_t *daBuf = readInt16(srcFilePath, no_ofelem );
printf("no_ofelem = %d \n",no_ofelem);
}
And this is the Arduino code:
#include <stdio.h>
#include <stdlib.h>
#include <SPI.h>
#include <SD.h>
int16_t *readInt16(char *srcFilePath, size_t *no_ofelem )
{
size_t inSize;
//------------------
if (!SD.begin(BUILTIN_SDCARD)) {
Serial.println("Failed to mount card () ");
while (1);
}
//open file for reading..
File pFile = SD.open(srcFilePath, FILE_READ);
if (!pFile) {
Serial.println("Opening file to read failed 1() ");
return;
}
inSize = pFile.size(); //pFile.position(); //ftell(pFile);
Serial.printf("inSize = %d \n",inSize);
no_ofelem = inSize/sizeof(int16_t); ///2;
Serial.printf("no_ofelem = %d \n",no_ofelem);
pFile.close();
if(inSize<=0)
{
Serial.printf("Error: input file is wrong!\n");
}
int16_t *daBuf = (int16_t *)malloc(inSize);
//open file for reading..
pFile = SD.open(srcFilePath, FILE_READ);
if (!pFile) {
Serial.println("Opening file to read failed ()2 ");
return;
}
pFile.read(daBuf, *no_ofelem );
pFile.close();
return daBuf;
}
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
while (!Serial) {};
size_t *no_ofelem ;
char srcFilePath[]="test_.txt";
int16_t *daBuf = readInt16(srcFilePath, no_ofelem );
Serial.printf("no_ofelem = %d \n",no_ofelem);
}
void loop() {
// put your main code here, to run repeatedly:
}
The output in C code is inSize = 5004 no_ofelem = 2502
In arduino: inSize = 87714 no_ofelem = 43857
test_.txt (4.9 KB)
Are you sure that the C code that you poted does what you want ?
From https://cplusplus.com/reference/cstdio/ftell/?kw=ftell
long int ftell ( FILE * stream );
Get current position in stream
Returns the current value of the position indicator of the stream.
So, if you fseek() to the end of the file then the ftell() function will return the number of bytes in the file. How does dividing that by 2 tell you how many "elements" there are in the file ?
The test.txt file that you posted is a binary file, not a text file. Where did it originate from ?
In C, the writing in the file :
fwrite(&variable ,sizeof(int16_t),1,file);
Try writing 100 ints to the file using your C code then counting the number of "elements" using your C code
What do you expect the number of "elements" to be ?
What is the number of "elements" returned ?
Please I need help to get on the number of values in txt file. How can do that?
The txt file like this:
16 -1 -1 0 19 1 0 0 4 -4 -7 -4 0 0 0 2 1 2 1 0 1 1 1 -2 4 0 0 0 -1 12 -6 1 0 2 -4 -1 1 1 14 0 1 1 -2 1 0 1 -1 0 0 0 0 -1 16 19 -5 0 7 -6 -2 14 -4 0 0 0 0 0 0 0 -2 4 -5 5 6 -3 -7 -4 0 3 3 0 0 0 0 0 0 0 0 -1 -1 0 0 0 0 0 1 -27 3 15 10 2 2 0 1 -2 6 2 -4 -1 0 0 0 0 0 -2 -2 1 10 2 6 0 0 11 -2 -7 -1 0 0 0 0 0 0 0 1 1 0 21 0 0 -1 4 -5 -8 -4 1 0 0 1 0 0 1 0 0 -1 1 -2 2 0 1 0 0 0 0 -1 15 -8 -2 -4 3 -1 0 -1
Any help please?
One good starting point would be to count the number of ‘spaces’…?
No, I need just the number of values.
number of values is a number of spaces +1, but counting the spaces will be more easy task than counting the values.
@mercala_eng
Why did you opened a second topic with the same problem? - It is a violation of the forum rules. Please keep your discussion in the first thread:
There are no spaces between the single digit integers.
Could you show us the code you have so far please?
Sure looks to me like there are:
If there weren't space, they wouldn't be "single-digit" integers!
Are you sure? 
If there are "single digit integers"
1 2 4 8 9
so they has a spaces between it.
If there are something like
111
there is no spaces between digits, but it is not a "single digit".
You’re both right, sorry, I’ll change my optician. 
Maybe it is a different problem? That other thread (despite its title) was about a binary file - not a text file. 
@mercala_eng - if you've given up on that other thread, then please add a note there to the people who have been trying to help you with it.