i am very new to C but making my way through.
im using calls to a shared lib for controlling a robotics microcontroller.
a function, defined in the header, like this:

aServo_GetPosition(stem, GPMOD, SRV2, srv1pos);

it gets the position of a servo and puts the value in srv1pos an 'unsigned char'.
the result is a number between 0 and 255.

printf("servo postion = %d\n", srv1pos);

yeilds # servo position = 178

so all i want to do is to put that '178' into a file.

i have defined another function where the file is to be written
and i want to pass 'srv1pos' as a variable to that function.
i've tried using fputc(), fputs() and fwrite() and i just can't get it to work.

thanks in advance for any help

Can you post any code?

did you open the file first? (you have to open a defined file b4 you can do anyhting to it)

Have u checked the return values of those fp.. functions.
Post your code than only i can help you.

if you want it to be displayed in human-readable form you should use fprintf (same as printf but takes a filehandle too)

so here is the relevant code.

/* filewriter */

int filewriter(char wfilename[], int wdata)
{
FILE *wstemdev;
char buff;
buff = wdata;
enum {WSUCCESS, WFAIL};
int wreval = WSUCCESS;
if ((wstemdev = fopen(wfilename, "w")) == NULL){
wreval = WFAIL;
return 1;
}
else
{
fputc( buff, wstemdev);
fclose(wstemdev);
}
}

/* this gets the servo position */

iwErr = aServo_GetPosition(stem, GPMOD, SRV1, &srv0posloop);
filewriter("../stem/servo/servo-0", srv0posloop);


im going to try using fprintf() that sounds promising.
thanks for all replies

fprintf("%d\n",buff);

will print '178' to the file.

i got it.

int filewriter(char wfilename[], int wdata)
{
FILE *wstemdev;
enum {WSUCCESS, WFAIL};
int wreval = WSUCCESS;
if ((wstemdev = fopen(wfilename, "w")) == NULL){
wreval = WFAIL;
return 1;
}
else
{
fprintf( wstemdev, "%d\n", wdata);
fclose(wstemdev);
}
}

fprintf() was what i needed.
now i need to figure out how to get the same data back out.
i'll work on it for a bit before i bug you guys again.

thanks alot.
i love this place

er.. fscanf ??

right so i'm trying to use scanf() like this


int filewriter(char wfilename[], int wdata)
{
FILE *wstemdev;
enum {WSUCCESS, WFAIL};
int wreval = WSUCCESS;
if ((wstemdev = fopen(wfilename, "w")) == NULL){
wreval = WFAIL;
return 1;
}
else
{
fprintf( wstemdev, "%d\n", wdata);
fclose(wstemdev);
}
}

int main()
{
unsigned char s1l, srv1posloop;
while(1)
{
iwErr = aServo_GetPosition(stem, GPMOD, SRV1, &srv0posloop);
filewriter("../stem/servo/servo-0", srv0posloop);
FILE *dest0devr;
enum {SD0SUCCESS, SD0FAIL, SD0MAX_LEN = 81};
unsigned char sd0value[SD0MAX_LEN];
int sd0evalr = SD0SUCCESS;
if ((dest0devr = fopen("../stem/servo/dest-0", "r")) == NULL){
sd0evalr = SD0FAIL;
return;
}
else
{
fscanf(dest0devr, "%d" , &sd0value);
fclose(dest0devr);
iwErr = aServo_SetPositionAbs(stem, GPMOD, SRV1, sd0value);
}
}
}

but it doesn't work like expected
../stem/servo/dest-0 contains 127
the servo should move to match this number after it is gotten from the file
by fscanf()
but instead it moves to 224
all the values i put into files with aServo_GetPosition() and filewriter() are correct, but the values i get out with fscanf dont work properly
in aServo_SetPositionAbs().