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Variable is undeclared?

AmmmG 01 (51)
It says that the variables at int main (line 77) are undeclared.
it is a simple program so just help me understand that silly yet confusing mistake.

Appreciated.

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#include<iostream>
using namespace std;
class queue {
public:
	void queue_init(int size);
	void push(char x);
	void pop();
	int size();
	char front();
	char back();
	int Empty();
	int full();


private:
	char* queue_ptr;
	int max_len;
	int rear_cnt;
	int front_cnt;
};

int queue::size() {
	return (rear_cnt - front_cnt);
}

void queue::queue_init(int arr_size) {
	queue_ptr = new char[arr_size];
	max_len = arr_size - 1;
	front_cnt = 0;
	rear_cnt = 0;
}

int queue::Empty() {
	return (rear_cnt == front_cnt);
}

int queue::full() {
	return (rear_cnt == max_len + 1);
}
char queue::front() {
	return (queue_ptr[front_cnt]);
}

char queue::back() {
	return (queue_ptr[rear_cnt - 1]);
}

void queue::push(char X) {
	if (rear_cnt == max_len + 1)
		cout << "Error queue is full \n";
	else
	{
		queue_ptr[rear_cnt] = X;


		rear_cnt++;
	}
}

void queue::pop() {

	if (Empty())
		cout << "Error queue is empty\n";
	else
	{
		queue_ptr[front_cnt] = 0;
		front_cnt++;
	}
}



int main(){
	queue Q;
	int time = 810;
	Q.queue_init(10);
	char a, b, c, d, e, f, g, h, j, k, l;
	cout << "This program will calculate the customer service throughout the next 30 minutes.\n"
		"Since a customer enters Rajhi Bank every 3 minutes, therefore the size of the queue should be 10 or a possible 11." << endl;
	cout << "The customer service opens at 8:10 am" << endl;
	for (int i = 0; i <= 30; i++)
	{
		if (i = 0) {
			cout << "it is 8:10 am. The first customer just arrived." << endl;
			Q.push(a);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 3) {
			cout << "it is 8:13 am. The second customer just arrived." << endl;
			Q.push(b);
			cout << "There are: "; Q.size(); cout << "waiting on line currently." << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;

		}
		if (i = 5){
			cout << "it is 8: 15 am. The first customer is served." << endl;
			Q.pop();
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}

		if (i = 6){
			cout << "it is 8: 16 am. The third customer just arrived." << endl;
			Q.push(c);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 9){
			cout << "it is 8: 19 am. The fourth customer just arrived." << endl;
			Q.push(d);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 10){
			cout << "it is 8: 20 am. The second customer is served." << endl;
			Q.pop();
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 12){
			cout << "it is 8: 22 am. The fifth customer just arrived." << endl;
			Q.push(e);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 15){
			cout << "it is 8: 25 am. The sixth customer just arrived." << endl;
			Q.push(f);
			cout << "and the third customer just got served."; Q.pop(); cout << endl;
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 18){
			cout << "it is 8: 28 am. The seventh customer just arrived." << endl;
			Q.push(g);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 20){
			cout << "it is 8: 30 am. The fourth customer just got served." << endl;
			Q.pop();
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 21){
			cout << "it is 8: 31 am. The eighth customer just arrived." << endl;
			Q.push(h);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 24){
			cout << "it is 8: 34 am. The ninth customer just arrived." << endl;
			Q.push(j);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 25){
			cout << "it is 8: 35 am. The fifth customer just got served." << endl;
			Q.pop();
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 27){
			cout << "it is 8: 37 am. The tenth customer just arrived." << endl;
			Q.push(j);
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
		if (i = 30){
			cout << "it is 8: 40 am. The eleventh customer just arrived." << endl;
			Q.push(l);
			cout << "and the sixth customer just got served."; Q.pop(); cout << endl;
			cout << "There are: "; Q.size(); cout << "waiting on line currently" << endl;
			cout << "currently serving: "; Q.front(); cout << endl;
			cout << " ************************************************************************* " << endl;
		}
	}
	return 0;
}
Last edited on
jlb (4973)
Strange I don't seem to get any "undeclared" variable errors. However there are quite a few other problems you should look into fixing.

It appears that you don't know the difference between the assignment operator= and the comparison operator== for the first several problems.

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In function 'int main()':
83:12: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
89:12: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
97:12: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
105:12: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
112:12: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
119:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
126:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
133:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
141:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
148:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
155:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
162:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
169:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
176:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
183:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
75:6: warning: unused variable 'time' [-Wunused-variable]
77:34: warning: unused variable 'k' [-Wunused-variable]
91:12: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
107:12: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
114:12: warning: 'd' may be used uninitialized in this function [-Wmaybe-uninitialized]
128:12: warning: 'e' may be used uninitialized in this function [-Wmaybe-uninitialized]
135:12: warning: 'f' may be used uninitialized in this function [-Wmaybe-uninitialized]
143:12: warning: 'g' may be used uninitialized in this function [-Wmaybe-uninitialized]
157:12: warning: 'h' may be used uninitialized in this function [-Wmaybe-uninitialized]
164:12: warning: 'j' may be used uninitialized in this function [-Wmaybe-uninitialized]
185:12: warning: 'l' may be used uninitialized in this function [-Wmaybe-uninitialized]


AmmmG 01 (51)
Thanks for the quick reply.

well, yes. you can see the problem of "uninitialized" variables at the second half of the problems you are showing me.

How do I fix them?
TarikNeaj (2580)
If you're having trouble with initializing a variable, the solution would simply be to initialize them.

You are pushing the char variables a,b,c etc into the queue, but they're garbage. They have no value, you havent given them any value so they're value of garbage. when you do Q.push(c); what are you pushing into the queue? what is "c" equal to?
AmmmG 01 (51)
c is of type char. are you saying I should initialize it as char c = c;

?
TarikNeaj (2580)
char c = c;
Right idea, but not exactly like this. You need to put the char quotes around it.

char c = 'c';
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