Passing a string value to a function - How?

oakguy

Guys
I am working with my activity bot and was building this and playing with using function calls for the first time. All my functions worked except when I realized I did not know how to instantiate a string variable in Propeller C. In my Void Display function I wanted to pass a string value as to where my servo was looking. I realize that I could do it an easier way. I was just trying to pass a string value. But I could not even create one. Functions sure do clean up your code.



void Display(string pointer,int cmDist)
{
print("pointer = %d, cmDist = %d\n", pointer, cmDist);
}

Thanks
Oakguy



#include "simpletools.h"
#include "servo.h"
#include "ping.h"
#include "wavplayer.h"
int main()
{


int delay1 = 1000;
int delay2 = 3000;
int cmDist = 0;
pointer = ("Forward");
//Opening Wave file and Ping forward
PlayWav();
servo_angle(17, 900);
pause(2000);

while(1)
{
servo_angle(17, 0);
pause(delay1);
cmDist = ping_cm(8);
Buzzer();
pointer = "Right";
Display(pointer, cmDist);
pause(delay2);


servo_angle(17, 900);
pause(delay1);
cmDist = ping_cm(8);
Buzzer();
pointer = "Forward";
Display(pointer, cmDist);
pause(delay2);


servo_angle(17, 1800);
pause(delay1);
cmDist = ping_cm(8);
Buzzer();
pointer = "Left";
Display(pointer, cmDist);
pause(delay2);


servo_angle(17, 900);
pause(delay1);
cmDist = ping_cm(8);
Buzzer();
pointer = "Forward";
Display(pointer, cmDist);
pause(delay2);
}
}


void Display(string pointer,int cmDist)
{
print("pointer = %d, cmDist = %d\n", pointer, cmDist);
}


void PlayWav(void)
{
int DO = 22, CLK = 23, DI = 24, CS = 25;
int Buzzer = 4, Duration = 250, Frequency = 4000;


//Mount the SD Card
sd_mount(DO, CLK, DI, CS);
const char techloop[] = {"techloop.wav"};
//play intro sound file
wav_play(techloop);
wav_volume(9);
pause(3500);
wav_stop();
}


void Buzzer(void)
{
int Buzzer = 4, Duration = 150, Frequency = 4000;
freqout(Buzzer, Duration, Frequency); //pin, duration, frequency
}

Andy Lindsay (Parallax)

Here is a short example:

#include "simpletools.h"

void displayString(char *pointer);

int main()
{
  char s[] = "Test message";
  displayString(s);
  displayString("Another test message");
}

void displayString(char *pointer)
{
  print("string = %s\n", pointer);
}

The output is:

oakguy

Thank you! I tried defining char s[] since it appeared that we instantiated an array. I have not grasped the logic yet. IDE errors with conflicting types for s. If I wanted to pass several different string values to a function, what is the correct syntax?


char s[1] = "Right";
Display(s, cmDist);


char s[2] = "Forward";
Display(s, cmDist);


char s[3] = "Left";
Display(s, cmDist);

Oakguy

Andy Lindsay (Parallax)

For a little more, take a look at XBee Command Mode Example.c in this post:

http://forums.parallax.com/showthread.php/152879-How-to-use-XBee-with-Activity-Board?p=1232211&viewfull=1#post1232211

Andy Lindsay (Parallax)

Also, I'd recommend moving sd_mount from PlayWav to just before the while(1) loop in main. ...and put int DO = 22, CLK = 23, DI = 24, CS = 25; above the main function.