Why can't my program show Fibonacci series? - c++

Question

My program can not show Fibonacci series but I think the code is right does anyone know why?
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <math.h>
using namespace std;
int main()
{
int a=0,b=1,c;
cout << "Fibonacci number" << endl;
cout << a << " ";
cout << b << " ";
while (c<100)
{
c=a+b;
a=b;
b=c;
}
cout << c << " ";
return 0;
}

Answer 1

There are two errors in your code, as already stated in the comments by someone else.
First, you are trying to use c without initializing it. Remember that in C++, when declaring a built-in type without initializing it, it is 'default initialized'. In other words, if you declare a variable of built-in type inside a function (in this case the main() function), it's value is undefined. Thus, you can't use it to check for a condition before assigning a value to it, and this is precisely what your while loop does.
Second, you are only pushing into the ostream the last calculated value of c. In other words, you are only printing the last value of you Fibonacci sequency.
Try putting your cout << c statement inside your loop.
PS.: Use the C++ version of C libraries whenever possible (i.e. <cstdio> instead of <stdio.h>, etc)