[Chimera9]

using namespace std;
# include <iostream>
# include <string>
# include <iomanip>
# include <vector>
 
double a;
double b;
double h;
 
double f(double x) {
     return x* - 1;
}
double sign(double x) {
     if (x < 0) {
          return 0;
     }
        else {
             return 1;
        }
}
double FindRoot (double a,double b,double h) {
double s;
double x;
s=sign(f(a));
while (s = sign(f(x))) {
  for (x=0; x < b; x=(a+b)/h)
return x;
}
}
double root=FindRoot (a, b, h);
void PrintResults ( double a, double b, double root) {
cout << "A root of the function f(x)=x^2-1 between " << a << " and " << b << " is " << root << endl << flush;
}
 
int main( ) {
PrintResults (-2,0,0.01);
  return 0;
}

I'm unsure why nothing's being printed. I'm guessing something's wrong with the format of PrintResults or my formula for finding the root is incorrect. Help wanted urgently. Thank you.

[virxen]

one error is this ---> while (s == sign(f(x))) {
and another is this -->return x*x - 1;

[Chimera9]

I fixed those errors (thanks for catching those, by the way), but still nothing is being printed.

[SaswatPadhi]

Found the error
Change :

double root=FindRoot (a, b, h);

to

double root;

First, you are trying to initialize a global var root outside any procedure.
Second, the vars that you pass as args : a, b, h to FindRoot are un-initialized !

Change the code and it should print.

[davidk]

Place this line

double root=FindRoot (a, b, h);

inside your PrintResults() function, or initialize 'root' variable inside main().

[virxen]

another error is this

Quote:

for (x=0; x < b; x=(a+b)/h)
return x;

no need for for command just put return 0; its the same!
No command is executed after a return!!!

and of course as davidk and SaswatPadhi said change your code like this

using namespace std;
# include <iostream>
# include <string>
# include <iomanip>
# include <vector>
 
//double a;
//double b;
//double h;
  .......
int main( ) {
double a=-2,b=0,h=0.01;
    double root=FindRoot (a, b, h);
    PrintResults (a,b,root);
.............

[Chimera9]

Thanks for all the help guys! I finally got it right with a little input from my instructor though. But again, thanks for taking the time to help.