Interpreting sensor input for robot.

Using Arduino Sensors
28

Crock101:
Is this better or am I still doing something wrong?

#include <Wire.h>

const int pingPin = 7;
int LeftF= 5;
int RightF= 2;
int LeftB= 3;
int RightB= 4;
void setup()
{
  pinMode(RightF,OUTPUT);
  pinMode(LeftF,OUTPUT);
  pinMode(LeftB,OUTPUT);
  pinMode(RightB,OUTPUT);
  Wire.begin();
  Serial.begin(9600);
}

void loop() {

while(Wire.available())   
  {
    Wire.requestFrom(2, 6);
    char c = Wire.read();   
    Serial.print(c);         
  }

long duration, inches, cm;

pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);

pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);

inches = microsecondsToInches(duration);
  cm = microsecondsToCentimeters(duration);

Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();

delay(100);
}

long microsecondsToInches(long microseconds)
{
  return microseconds / 74 / 2;
}

long microsecondsToCentimeters(long microseconds)
{
  return microseconds / 29 / 2;
}

if (c == )
  {
    digitalWrite(RightF,HIGH);
    digitalWrite(LeftB,HIGH);
    digitalWrite(RightB,LOW);
    digitalWrite(LeftF,LOW);
  }

if (c == )
  {
    digitalWrite(LeftF,HIGH);
    digitalWrite(RightB,HIGH);
    digitalWrite(RightF,LOW);
    digitalWrite(LeftB,LOW);
  }

if (c == ) and (inches > 12)
  {
    digitalWrite(LeftF,HIGH);
    digitalWrite(RightF,HIGH);
    digitalWrite(RightB,LOW);
    digitalWrite(LeftB,LOW);
  }

if (c == ) and (inches < 3)
  {
    digitalWrite(LeftB,HIGH);
    digitalWrite(RightB,HIGH);
    digitalWrite(RightF,LOW);
    digitalWrite(LeftF,LOW);
  }
  if (c == ) and (inches <= 12) and (inches >= 3)
  {
    digitalWrite(LeftB,LOW);
    digitalWrite(RightB,LOW);
    digitalWrite(RightF,LOW);
    digitalWrite(LeftF,LOW);
  }
}

still a lot i'm afraid;
aside from the c==<<no value>>;
you need to look up Arduino - Home to find out how to use Boolean Operators.

have you tried to verify that code ?
always use Ctrl-T & Ctrl-R (Shortcut for "Verify" button) to make sure your code is okay - compiler-wise.