celsius to fahrenheit for loop question

[halcolm1]

im trying to write a loop which will show when Celsius equals fahrenheit.
The loop counts down from Celsius = 100degrees and the loop stops when the 2 temperature measures are equal.

the formula to convert the 2 is:
fahrenheit = ((9* celsius)/5)+32)

I keep getting following warning in row 9 & 12 (aka 12|warning: 'c' is used uninitialized in this function [-Wuninitialized]

also, the loops continues to run to celsius equals -42 degrees, however it should stop at -40 degrees?

any help would be most appreciated

#include <iostream>
using namespace std;

int main()
{
int c, f;

 for(int c(100); f != c ; c--)
 {f = ((9* c)/5)+32;
    cout << c << "\t" << f << endl;
 }
    if(f == c)
    cout << " f equals c at degree " << c << endl;
    return 0;
}

[boost lexical cast]

Why are you declaring c in two places? Lines 6 & 8. Declare c in one place and initialize it to 100. As for f, first initialize it to 100 degrees Celsius converted to Fahrenheit (212).