Trigonometry

[xsxs]

Hi, I am trying to make a trig calculator.

#include<iostream>
#include<cmath>
using namespace std;
int main (){
cout<<"Hello, welcome to xxxx trig. calculator"<<endl;
cout<<"enter 1 for tan, enter 2 for sin, enter 3 for cos"<<endl;
	int select;
	cin>>select;
	
	do{	double a;
		cout<<"length of one side"<<endl;
		cin>>a;
		double b;
		cout<<"enter angle"<<endl;
		cin>>b;
		double radian=(b*3.14159/180);
		double unknownS=tan(radian)*a;
		cout<<"unknown length"<<unknownS<<endl;
	}
	while(select=='1');
	 
	do{
		double a;
		cout<<"length of one side"<<endl;
		cin>>a;
		double b;
		cout<<"enter angle"<<endl;
		cin>>b;
		double radian=(b*3.14159/180);
		double unknownS=sin(radian)*a;
		cout<<"unknown length"<<unknownS<<endl;
	}

	while(select=='2');

	do{
		double a;
		cout<<"length of one side"<<endl;
		cin>>a;
		double b;
		cout<<"enter angle"<<endl;
		cin>>b;
		double radian=(b*3.14159/180);
		double unknownS=cos(radian)*a;
		cout<<"unknown length"<<unknownS<<endl;
	}
	while(select=='3');
return 0;
}

My problem is that I want the user to choose sin, tan or cos by entering 1,2, or 3, but my code isn't allowing me to do that. It is outputting everything. I am wondering if there is a way to fix this problem. Thanks very much for your time.

[vlad from moscow]

The code you showed shall not be compiled. So iat least try to write code that is compiled without errors.

[Rechard3]

do not use do-while loops, you need a normal while loop for this problem.

[xsxs]

sorry, i forgot one of the do{

[vlad from moscow]

The condition in the do-while loop is incorrect

while(select=='1');

You are entering an integer number form 1 to 3 inclusively but trying to compare it with character '1'.

I think you meant

while( select < 1 || select > 3 );

[andywestken]

Going by the instuctions you display

enter 1 for tan, enter 2 for sin, enter 3 for cos

it looks like you to calculate a tangent value, if the user enters 1; calculate a sine value, if the user enters 2; and calculate a cosine value, if the user enters 3.

Also, as select is an int, this

select=='1'

is comparing select against the ascii code value for the character '1', which is 49 in decimal.

Andy

[Rechard3]

try this:

#include<iostream>
#include<cmath>
using namespace std;
int main (){
cout<<"Hello, welcome to xxxx trig. calculator"<<endl;
cout<<"enter 1 for tan, enter 2 for sin, enter 3 for cos"<<endl;
	char select;
	cin>>select;
	
	while(select=='1'){
		double a;
		cout<<"length of one side"<<endl;
		cin>>a;
		double b;
		cout<<"enter angle"<<endl;
		cin>>b;
		double radian=(b*3.14159/180);
		double unknownS=tan(radian)*a;
		cout<<"unknown length"<<unknownS<<endl;
	}
		 
	while(select=='2'){
		double a;
		cout<<"length of one side"<<endl;
		cin>>a;
		double b;
		cout<<"enter angle"<<endl;
		cin>>b;
		double radian=(b*3.14159/180);
		double unknownS=sin(radian)*a;
		cout<<"unknown length"<<unknownS<<endl;
	}


	while(select=='3'){
		double a;
		cout<<"length of one side"<<endl;
		cin>>a;
		double b;
		cout<<"enter angle"<<endl;
		cin>>b;
		double radian=(b*3.14159/180);
		double unknownS=cos(radian)*a;
		cout<<"unknown length"<<unknownS<<endl;
	}
return 0;
}

anyway, this still is a lame way to keep the choice repeating.
i didn't check your maths in this program, that's your job.

edit: i changed select from int to char

[vlad from moscow]

@Rechard3

Your proposed code is invalid. Please before posting read what others already wrote.

[Rechard3]

@vlad from moscow:

Please before posting read what others already wrote.

i did read the other posts, i still don't know which one you're talking about !!!

[Rechard3]

ok vlad from moscow, i'm now looking at the date you posted your comment, and the date i edited mine (the one right before it).

looks like you commented right before i submitted my edit.
i think you didn't read the edit.
anyway, after i read yours, i went to my C++ compiler and pasted that code in it, and tried the program myself.
it works like charm.

don't take it hard on me, i felt like my first contribution was discarded, that's why i posted the second.