Set the global variable has some question

Projects Programming
1

When we add the "float a1,b1;" this program can not into "void setup".
We just set the variable. But we can't run the program.

#include <NewSoftSerial.h>            // Add to library folder
#include <TinyGPS.h>  // Add to library folder
#include <string.h>
float a1,b1; //add this row,the program can not into the "void setup"
double d1,d2;
char *pEnd;
TinyGPS gps;
NewSoftSerial nss(7, 255);            // Yellow wire to pin 6
char value[20];
int i;

void setup() 
{
  Serial.begin(9600);
  nss.begin(4800);
  Serial.println("Reading GPS");
  delay(1000);
wait:
  if(Serial.available()>0)
  {
    for(i=0;i<20;i++)
    {
    value[i] = Serial.read();
    }
    Serial.println(value);
    char *pEnd;
    d1=strtod(value,&pEnd);
    d2=strtod(pEnd,NULL);
    Serial.println(d1,6);
    Serial.println(d2,6);
    goto wait2;
  }
  else
  {
  //Serial.println('1');
  goto wait;
  }
wait2:delay(500);
}
void loop() {
  Serial.println('2');
  bool newdata = false;
  unsigned long start = millis();
  while (millis() - start < 5000) {  // Update every 5 seconds
    if (feedgps())
      newdata = true;
  }
  if (newdata) {
    gpsdump(gps);
  }
}

// Get and process GPS data
void gpsdump(TinyGPS &gps) {
  float flat, flon, x,y,lat2,long2,d3,d4,d5,d6,d7,a3,a4,a5,a6,a7,c;
  unsigned long age;
  gps.f_get_position(&flat, &flon, &age);
  x=flat,y=flon;
  Serial.print(x, 6); Serial.print(", "); 
  Serial.println(y, 6);
  float course_to (float x, float y, float d1, float d2);
  {
    if ((d2-y)<0)
    {
d3=(24-x)*111.11111*1000;
d4=(sqrt(sq(d1-x)+sq(d2-y)))*111.11111*1000;
  d5=(sqrt(sq(d2-y)+sq(d1-24)))*111.11111*1000;
  d6=((sq(d3)+sq(d4)-sq(d5))/(2*d3*d4));
  d7=((acos(d6))*57.29578)*(-1);
    }
    else
    {
    d3=(24-x)*111.11111*1000;
d4=(sqrt(sq(d1-x)+sq(d2-y)))*111.11111*1000;
  d5=(sqrt(sq(d2-y)+sq(d1-24)))*111.11111*1000;
  d6=((sq(d3)+sq(d4)-sq(d5))/(2*d3*d4));
  d7=((acos(d6))*57.29578);
}
    if((y-b1)<0)
    {
  a3=(24-a1)*111.11111*1000;
  a4=(sqrt(sq(x-a1)+sq(y-b1)))*111.11111*1000;
  a5=(sqrt(sq(y-b1)+sq(x-24)))*111.11111*1000;
  a6=((sq(a3)+sq(a4)-sq(a5))/(2*a3*a4));
  a7=((acos(a6))*57.29578)*(-1);
    }
  else if((y-b1)>0)
  {
      a3=(24-a1)*111.11111*1000;
  a4=(sqrt(sq(x-a1)+sq(y-b1)))*111.11111*1000;
  a5=(sqrt(sq(y-b1)+sq(x-24)))*111.11111*1000;
  a6=((sq(a3)+sq(a4)-sq(a5))/(2*a3*a4));
  a7=((acos(a6))*57.29578);
  }
  else
  {
    a7=0;
  }
  c=a7-d7;
  Serial.println(c,6);  //delta angle,H-T
  Serial.println(d4,6); //car to target distance
  Serial.println(d7,6); //cat to target angle
  a1==x,b1==y;
}
}
// Feed data as it becomes available 
bool feedgps(){
  while (nss.available()) {
    if (gps.encode(nss.read()))
      return true;
  }
  return false;
}

Moderator edit: Replace quote tags with

2

Lose the gotos, then we can talk

if(Serial.available()>0)
  {
    for(i=0;i<20;i++)
    {
    value[i] = Serial.read();
    }

Let's all recite the mantra: "See if there's at least one character available in the receive buffer, then go ahead and read all twenty of them...oooooommmmm"

d1=strtod(value,&pEnd);

Risky strategy, relying on the the left-over nulls in the array to terminate your string for you, 'cos there aren't any.

3

How to record and access the latitude and longitude
d1=latitude
d2=longitude

    char *pEnd;
    d1=strtod(value,&pEnd);
    d2=strtod(pEnd,NULL);
    Serial.println(d1,6);
    Serial.println(d2,6);

Moderator edit: quote tags swapped for code tags.

4

Posting snippets is just a waste of time.

Did you read my comments yesterday here about terminating strings?

5

I see what you did there. You ignored the advice in the earlier thread and started a new one.

Threads merged.

Don't keep doing that please. If you don't understand the advice, say so.

6

For help, you need to post all you code.
Hopefully by now, you'll have corrected the serial reading so that you wait for each character to be available before reading it (or waiting until all the characters you expect are available) and got rid of the "goto"s, and terminated the string before calling any string operations.