Square Root...

[CyberCarsten]

I have been trying to take the square root of a number by doing this:

a = Sqr(25);

And

a = Sqrt(25);

I get the following error:error C2065: 'Sqr' : undeclared identifier

and error C2065: 'Sqrt' : undeclared identifier....

What is wrong?

[Vlatko]

Include the math.h header file.

#include <math.h>
...
double root = sqrt(nymber);

[parksie]

It's in the math.h system header, and since it's a library function it's all lower case:

float x = sqrt(5.4f);

[parksie]

I'll let you have that one

parksie 1 - 1 Vlatko

[CyberCarsten]

Now I get the error:

C:\Programmer\Microsoft Visual Studio\MyProjects\Equation\equation.cpp(41) : error C2361: initialization of 'x' is skipped by 'default' label
C:\Programmer\Microsoft Visual Studio\MyProjects\Equation\equation.cpp(37) : see declaration of 'x'

[parksie]

What's at those lines?

[CyberCarsten]

switch(choice){
	case 1 : 
		// Do actions
	break;
	case 2 : 
		cout<<"Input a: ";
		cin>>a;

		cout<<""<<endl;

		cout<<"Input b: ";
		cin>>b;

		cout<<""<<endl;

		cout<<"Input c: ";
		cin>>c;

		d = b * b - 4 * a * c;
		cout<<d<<endl;
		double x = sqrt(d);
		
		l1 = -b - x / 2 * a;
		l2 = -b + x / 2 * a;
		
		cout<<""<<endl;
		
		cout<<"L1: " <<l1<<endl;
		cout<<"L2: " <<l2<<endl;
	
	break;
	default:
		cout<<"Choose either 1 or 2"<<endl;
	}

[parksie]

You'll need to put the definition for double x before the switch block.

[CyberCarsten]

Now I get the following error:

:\Programmer\Microsoft Visual Studio\MyProjects\Equation\equation.cpp(16) : error C2086: 'x' : redefinition
C:\Programmer\Microsoft Visual Studio\MyProjects\Equation\equation.cpp(40) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
C:\Programmer\Microsoft Visual Studio\MyProjects\Equation\equation.cpp(41) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
C:\Programmer\Microsoft Visual Studio\MyProjects\Equation\equation.cpp(49) : error C2361: initialization of 'x' is skipped by 'default' label
C:\Programmer\Microsoft Visual Studio\MyProjects\Equation\equation.cpp(37) : see declaration of 'x'

double x;
	switch(choice){
	case 1 : 
		// Do actions
	break;
	case 2 : 
		cout<<"Indtast a: ";
		cin>>a;

		cout<<""<<endl;

		cout<<"Indtast b: ";
		cin>>b;

		cout<<""<<endl;

		cout<<"Indtast c: ";
		cin>>c;

		d = b * b - 4 * a * c;
		cout<<d<<endl;
		double x = sqrt(d);
		cout<<x<<endl;

		l1 = -b - x / 2 * a;
		l2 = -b + x / 2 * a;
		
		cout<<""<<endl;
		
		cout<<"L1: " <<l1<<endl;
		cout<<"L2: " <<l2<<endl;
	
	break;
	default:
		cout<<"Choose either 1 or 2"<<endl;
	}

[parksie]

Obviously you need to take out the second definition

Try initialising it to 0 at the start, though.