how do I wrtie a function that takes one argument of type double. The function returns the character value ā€˜Pā€™ if its argument is positive and return ā€˜Nā€™ if its argument is zero or negative.

double Letter ( double P, double N)

if (P = +);

return P;

else
 
return N

if ( P=0);

Does this look right?

>>Does this look right?
Close, but its not right

1) line 1: the function is supposed to return a char, not double. So you need to declare it as char Letter ( double P) 2) The function is only supposed to have one argument, not two.

3) You forgot the open and close braces around the body of the function.

4) line 3: remove the semicolon at the end of that line.

5) The return values on lines 5 and 9 are wrong. You are supposed to return the letter P is the parameter is a positive value. That means you have to compare the value of the parameter to 0. If greater than or equal to 0 then return 'P' otherwise return 'N'.

6) Delete line 11 because I have no idea what that is supposed to do.

char Letter ( double P, double N)
 {

if( P >= 0)

return P

else return N

}

How about this AD?

that's better but still not correct. You need to put single quotes around the P and N, like this: return 'P'; Also see my comment #2 in my previous post -- you didn't remove that second parameter.

Next you probably need to add a main() function so that your program will compile and link correctly.

so how do I return 'N' if I don't delcare it?

There is no need to initialise and declare the return value, in this case. It's returned directly without first assigning it to a variable. If you wanted to, you could initialise and assign to a char variable and then return that char variable - that is the same as return 'P'; .

Your function is designed to return a char value, as long as you return a char value everything is sweet. As AD mentioned, you don't need to pass a char variable as an argument, it serves no purpose.

int main()
{
   ...
   double P = 15.6;
   char z;
   z = Letter(P);
   ...
}

In the above example z will be assigned the return value (char) of the Letter(P) function.

Consider the following:

inline char IsPositive(double r) { return ( (r < 0.0) ? 'N' : 'P'); }
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