code for line following robot not working perfectly

Question

I have made a line following robot using 2 IR sensor. My line following robot was working successfully with this code.

#define LS 2 // left sensor
#define RS 3 // right sensor
/*-------definning Outputs------*/
int LM1= 5; // left motor
int LM2= 6; // left motor
int RM1= 9; // right motor
int RM2= 10;
void setup()
{
 pinMode(LS, INPUT);
 pinMode(RS, INPUT);
 pinMode(LM1, OUTPUT);
 pinMode(LM2, OUTPUT);
 pinMode(RM1, OUTPUT);
 pinMode(RM2, OUTPUT);
}
void loop()
{
 if(digitalRead(LS) && digitalRead(RS)) // Move Forward
 {
 digitalWrite(LM1, HIGH);
 digitalWrite(LM2, LOW);
 digitalWrite(RM1, HIGH);
 digitalWrite(RM2, LOW);
 }
 else if(!(digitalRead(LS)) && digitalRead(RS)) // Turn right
 {
 digitalWrite(LM1,HIGH);
 digitalWrite(LM2, LOW);
 analogWrite(RM1,70);
 digitalWrite(RM2,LOW);
 }
 else if(digitalRead(LS) && !(digitalRead(RS))) // turn left
 {
 analogWrite(LM1,70);
 digitalWrite(LM2, LOW);
 digitalWrite(RM1,HIGH);
 digitalWrite(RM2,LOW);
 }else{
 digitalWrite(LM1, LOW);
 digitalWrite(LM2, LOW);
 digitalWrite(RM1,LOW);
 digitalWrite(RM2, LOW);
 }
}

As I used only two sensor,sometimes it goes out of the line. So I have tried to make an advanced line following robot which could get back to track automatically when it goes out of the line.But the code is taking only the 1st value of tmp.(tmp=1) even when left sensor touches the line after white sensor and the robot goes out of the line.The value of tmp should be 2 when the robot goes out of the line and the left sensor touches the line after the white sensor. Here is the code:

/*-------definning Inputs------*/
#define LS 2 // left sensor
#define RS 3 // right sensor
/*-------definning Outputs------*/
int LM1= 5; // left motor
int LM2= 6; // left motor
int RM1= 9; // right motor
int RM2= 10; //right motor
int tmp;
void setup()
{
 pinMode(LS, INPUT);
 pinMode(RS, INPUT);
 pinMode(LM1, OUTPUT);
 pinMode(LM2, OUTPUT);
 pinMode(RM1, OUTPUT);
 pinMode(RM2, OUTPUT);
}
void loop()
{
 if(digitalRead(LS) && digitalRead(RS)) // Move Forward
 {
 digitalWrite(LM1, HIGH);
 digitalWrite(LM2, LOW);
 digitalWrite(RM1, HIGH);
 digitalWrite(RM2, LOW);
 }
 else if(!(digitalRead(LS)) && digitalRead(RS)) // Turn right
 {
 digitalWrite(LM1,HIGH);
 digitalWrite(LM2, LOW);
 analogWrite(RM1,70);
 digitalWrite(RM2,LOW);
 tmp=1;
 }
 else if(digitalRead(LS) && !(digitalRead(RS))) // turn left
 {
 analogWrite(LM1,70);
 digitalWrite(LM2, LOW);
 digitalWrite(RM1,HIGH);
 digitalWrite(RM2,LOW);
 tmp=2;
 }
 else//out of the line
 {
 if(tmp=1){
 analogWrite(LM1,70);
 digitalWrite(LM2, LOW);
 digitalWrite(RM1,LOW);
 analogWrite(RM2,70);
 }else if(tmp=2){
 digitalWrite(LM1,LOW);
 analogWrite(LM2, 70);
 analogWrite(RM1,70);
 digitalWrite(RM2,LOW);
 }
 }
}

Answer 1

This test:

if (tmp = 1)

is always true. You are assigning 1 to tmp and that value (1), when interpreted in a boolean context (i.e. as a truth value), is true.

You probably mean

if (tmp == 1)

and similarly for the next test.