Help wit C++

here are my practice problems:


the answers that i have are at the bottom.(if you guys can check it and provide the right answer if i got it wrong, that would be great)



5. Write a C++ statement that displays a random integer from 50 through 100 on the computer screen.

6. Write a C++ statement that assigns the square root of a number to a double variable named sqRoot. The number is stored in a double variable named num.

7. Write the C++ code for a function that prompts the user to enter a character and then stores the character in a char variable named response. The functions should return the contents of the response variable. Name the function getCharacter. (The function will not have any actual arguments passed to it.) Also write an appropriate function prototype for the getCharacter function. In addition, write a statement that invokes the getCharacter function and assigns its return value to a char value named custCode.

8. Write the C++ code for a function that receives four double numbers. The function should calculate the average of the four numbers and then return the result. Name the function calcAverage. Name the formal parameters num1, num2, num3, num4. Also write an appropriate function prototype for the calcAverage function. In addition, write a statement that invokes the calcAverage function and assigns its return value to a double variable named quotient. Use the following numbers as the actual arguments: 45.67, 8.35, 125.78, 99.56.

9.Write the C++ statement that adds the cube of the number stored in the num1 variable to the square root of the number stored in the num2 variable. The statement should assign the result to the answer variable. All of the variables have the double data type.

10. Write a C++ statement that assigns to the answer variable the square root of the following expression: x^2 * y^3. The x,y and answer variable have the double data type.

5. 1 + 50 % (100 – 50 + 1)
6. sqRoot (num)
7. char getcharacter (char)
cout<<”Enter a character”:
cin>> response;
getcharacter (response)
{
return custcode;
} // end of getcharacter function
8.
9. answer = pow(num1) + sqrt(num2);
10. answer = pow(x,2) * pow(y,3);

#10 is correct. The rest are all wrong to some degree, although #9 is close.

#5 asks for a random number. Nothing in your statement is random.

#6 does not compute a square root.

#7 is vaguely headed in the right direction, but has a number of problems, the most obvious of which is----where did this "custcode" variable come from?

Quote:

---

Originally Posted by Lindley

#10 is correct. The rest are all wrong to some degree, although #9 is close.

#5 asks for a random number. Nothing in your statement is random.

#6 does not compute a square root.

#7 is vaguely headed in the right direction, but has a number of problems, the most obvious of which is----where did this "custcode" variable come from?

---

read the problem statement for number 7 and you will see the custCode variable.

Thanks so far though

Yes, I see the name mentioned in the problem. But you still do not appear to understand what the problem is asking you to do:

Quote:

---

7. Write the C++ code for a function

---

So, you're going to need a function. So far so good.

Quote:

---

that prompts the user to enter a character and then stores the character in a char variable named response.

---

Still good so far, although you aren't actually declaring "response" anywhere before trying to use it.

Quote:

---

The functions should return the contents of the response variable. Name the function getCharacter. (The function will not have any actual arguments passed to it.)

---

Here we run into trouble. You've named the function getcharacter rather than getCharacter (capitalization is important). You've specified it takes a char argument when the question says it doesn't take any arguments. And you aren't returning the result variable.

Quote:

---

Also write an appropriate function prototype for the getCharacter function.

---

Tough to say whether any of the things you wrote were intended to be a prototype, but you need one and one isn't there.

Quote:

---

In addition, write a statement that invokes the getCharacter function and assigns its return value to a char value named custCode.

---

You are not doing this.

#5: google for "random numbers in c", I glanced at the top 3 results and 2 of them have enough information to answer this.
#6: reread the question... you correctly figured out the square root of something in #9, just do the same sort of thing and assign it to the variable they want
#7: yeah... start this one over... it doesn't bear anything but passing resemblance to the question
#8: Here, I'll get you started. "a function that receives four double numbers" might look like:

Code:

---

void question_eight(double numberA, double numberB, double numberC, double numberD)
{
 // This is a void function so doesn't need a return statement.
}

---

Now, the next thing it says is that it's going to have to return the average of the supplied numbers. So you'd pick a type of value to return (let's say a double), and replace the 'void' type with that type. There, you now have an empty function set up to take four doubles (but of course it needs to return something... and they have naming requirements that I didn't cover... and of course there's some math... and so forth).
#9: You used the 'pow' function correctly in #10, but not here.
#10: I don't see any square rooting being done here.

here are my updated answers(i will be working on number 7 and 8)

5. 50 + rand() % (100 – 50 + 1)
6. sqRoot = sqrt (num);
9. answer = pow(num1) + sqrt(num2);
10. answer = pow(x,2) * pow(y,3);

Quote:

---

Originally Posted by ade161

here are my updated answers(i will be working on number 7 and 8)

5. 50 + rand() &#37; (100 – 50 + 1)

---

Why 100 - 50 + 1? If you mean 51, write 51.
rand requires srand be called first.

Quote:

---

Originally Posted by ade161

here are my updated answers(i will be working on number 7 and 8)

6. sqRoot = sqrt (num);

---

You need to define sqRoot.

Quote:

---

Originally Posted by ade161

here are my updated answers(i will be working on number 7 and 8)


9. answer = pow(num1) + sqrt(num2);

---

I believe it's already been pointed out that you're not calling pow correctly, and again, you need to define your variables.

Quote:

---

Originally Posted by GCDEF

rand requires srand be called first.

---

In the context of this question I wouldn't worry about it. After all, we don't want them thinking they need to call srand() before *every* use of rand(), would we?

Quote:

---

Originally Posted by Lindley

In the context of this question I wouldn't worry about it. After all, we don't want them thinking they need to call srand() before *every* use of rand(), would we?

---

No we wouldn't, and the prof did ask for a single statement. Just making sure the OP knows how it works, and the prof may be looking for srand. I don't know.

Quote:

---

Originally Posted by GCDEF

I believe it's already been pointed out that you're not calling pow correctly, and again, you need to define your variables.

---

int num1 = 0;
int num2 = 0;
int answer = 0;
cout<<”Enter num 1 “;
cin>>num1;
cout<<”Enter num 2 “;
cin>>num2;
answer = pow(num1) + sqrt(num2);

Quote:

---

Originally Posted by ade161

int num1 = 0;
int num2 = 0;
int answer = 0;
cout<<”Enter num 1 “;
cin>>num1;
cout<<”Enter num 2 “;
cin>>num2;
answer = pow(num1) + sqrt(num2);

---

I don't know how many ways to say you're not calling pow correctly, and if you read the problem statement, you'll see the prof calls for a specific data type, and it wasn't int.

Quote:

---

Originally Posted by GCDEF

I don't know how many ways to say you're not calling pow correctly, and if you read the problem statement, you'll see the prof calls for a specific data type, and it wasn't int.

---

the syntax for the pow function is:

pow(x,y)




9. double num1 = 0;
double num2 = 0;
double answer = 0;
cout<<”Enter num 1 “;
cin>>num1;
cout<<”Enter num 2 “;
cin>>num2;
answer = pow(num1,3) + sqrt(num2);

My reading of the problem is that you only need the last line of that (but move the declaration of answer onto that line for completeness). However, the professor probably will accept that entire thing as the answer.

Quote:

---

Originally Posted by ade161

the syntax for the pow function is:

pow(x,y)




9. double num1 = 0;
double num2 = 0;
double answer = 0;
cout<<”Enter num 1 “;
cin>>num1;
cout<<”Enter num 2 “;
cin>>num2;
answer = pow(num1,3) + sqrt(num2);

---

Better. He doesn't ask you to input the numbers, but I don't imagine he'll take any points off if you do.

Quote:

---

Originally Posted by Lindley

My reading of the problem is that you only need the last line of that (but move the declaration of answer onto that line for completeness). However, the professor probably will accept that entire thing as the answer.

---

and you are referring to question 9?

Yes.

One thing to be careful about with pow() is that it doesn't have a form which takes pow(int,int). Therefore, at least one of the arguments must be a float or double. In this case, the first argument is a double, so you're fine; for your future reference, however, it might be slightly safer to write "pow(num1,3.0)" rather than "pow(num,3)". This makes the second argument a double as well rather than an int.

Quote:

---

10. Write a C++ statement that assigns to the answer variable the square root of the following expression: x^2 * y^3. The x,y and answer variable have the double data type.

---

Quote:

---

10. answer = pow(x,2) * pow(y,3);

---

Quote:

---

Originally Posted by Lindley

#10 is correct.

---

No, 10 is wrong. it doesn't calculate the required value, it only calculates part of the problem.

Yeah, I missed that part of it.

Quote:

---

Originally Posted by ade161

5. 50 + rand() % (100 – 50 + 1)

---

#5 is looking better, so far. You've generated your random number, now you just have to display it.

Quote:

---

Originally Posted by Ankheg

#5 is looking better, so far. You've generated your random number, now you just have to display it.

---

5. srand(static_casst<int>(time(0)));
50 + rand() % (100 – 50 + 1)
cout << rand () << endl;

No, you're supposed to display the number you just came up with, not a new random number.

Quote:

---

Originally Posted by OReubens

No, 10 is wrong. it doesn't calculate the required value, it only calculates part of the problem.

---

im glad that you caught that mistake

heres what i got

10. answer = sqrt(pow(x,2) * pow(y,3));

Quote:

---

Originally Posted by ade161

5. srand(static_casst<int>(time(0)));
50 + rand() &#37; (100 – 50 + 1)
cout << rand () << endl;

---

Again, what's the point in (100 – 50 + 1)? Just write the number.

Quote:

---

Originally Posted by GCDEF

Again, what's the point in (100 – 50 + 1)? Just write the number.

---

the syntax states:

lowerbound + rand() % (upperbound - lowerbound +1)

Quote:

---

Originally Posted by ade161

the syntax states:

lowerbound + rand() % (upperbound - lowerbound +1)

---

I know what you're doing. You should either #define constants for upper and lower bound, or just write 51. There's no point in writing a little arithmetic expression in there.

Quote:

---

Originally Posted by GCDEF

I know what you're doing. You should either #define constants for upper and lower bound, or just write 51. There's no point in writing a little arithmetic expression in there.

---

except for when i take a test the prof wants it that way

Quote:

---

Originally Posted by Ankheg

#5: google for "random numbers in c", I glanced at the top 3 results and 2 of them have enough information to answer this.
#6: reread the question... you correctly figured out the square root of something in #9, just do the same sort of thing and assign it to the variable they want
#7: yeah... start this one over... it doesn't bear anything but passing resemblance to the question
#8: Here, I'll get you started. "a function that receives four double numbers" might look like:

Code:

---

void question_eight(double numberA, double numberB, double numberC, double numberD)
{
 // This is a void function so doesn't need a return statement.
}

---

Now, the next thing it says is that it's going to have to return the average of the supplied numbers. So you'd pick a type of value to return (let's say a double), and replace the 'void' type with that type. There, you now have an empty function set up to take four doubles (but of course it needs to return something... and they have naming requirements that I didn't cover... and of course there's some math... and so forth).
#9: You used the 'pow' function correctly in #10, but not here.
#10: I don't see any square rooting being done here.

---

8. double calcAverage (double, double, double, double); // prototype
double calcAverage (double num1, double num2, double num3, double num4)
{
double quotient = 0.0;
quotient = (num1 + num2 + num3 + num4) / 4;
return quotient;
} // end of calcAverage function

Quote:

---

Originally Posted by ade161

8. double calcAverage (double, double, double, double); // prototype
double calcAverage (double num1, double num2, double num3, double num4)
{
double quotient = 0.0;
quotient = (num1 + num2 + num3 + num4) / 4;
return quotient;
} // end of calcAverage function

---

That'll work. Don't forget the second part of the problem.

In addition, write a statement that invokes the calcAverage function and assigns its return value to a double variable named quotient. Use the following numbers as the actual arguments: 45.67, 8.35, 125.78, 99.56.

Quote:

---

Originally Posted by GCDEF

That'll work. Don't forget the second part of the problem.

In addition, write a statement that invokes the calcAverage function and assigns its return value to a double variable named quotient. Use the following numbers as the actual arguments: 45.67, 8.35, 125.78, 99.56.

---

double calcAverage (double, double, double, double); // prototype

double calcAverage (45.67, 8.35, 125.78, 99.56) // invoke

double calcAverage (double num1, double num2, double num3, double num4)
{
double quotient = 0.0;
quotient = (num1 + num2 + num3 + num4) / 4;
return quotient;
} // end of calcAverage function

Quote:

---

Originally Posted by ade161

double calcAverage (45.67, 8.35, 125.78, 99.56) // invoke

---

Close

write a statement that invokes the calcAverage function and assigns its return value to a double variable named quotient

Quote:

---

Originally Posted by GCDEF

That'll work. Don't forget the second part of the problem.

In addition, write a statement that invokes the calcAverage function and assigns its return value to a double variable named quotient. Use the following numbers as the actual arguments: 45.67, 8.35, 125.78, 99.56.

---

7. cout<<”Enter a character”;
cin>>response;
char getCharacter (); // prototype
char getCharacter (); //invoke
{
return custCode;
}


is this right?

Quote:

---

Originally Posted by GCDEF

Close

write a statement that invokes the calcAverage function and assigns its return value to a double variable named quotient

---

quotient = double calcAverage (45.67, 8.35, 125.78, 99.56) invoke

Quote:

---

Originally Posted by ade161

quotient = double calcAverage (45.67, 8.35, 125.78, 99.56) invoke

---

You're getting really close now. The only definite problem with that is that you didn't end the statement (add a ; ) and the "invoke" needs to be a comment.

You do have another potential problem though... but it's entirely a social one. It could be assumed from the problem that the double named quotient already exists. But it could also be assumed that it doesn't. I think it would be safer if you explicitly defined quotient as a variable in your answer.

Another suggestion I have is for your prototype. Personally I would prototype it as:
double calcAverage (double num1, double num2, double num3, double num4);

This has two advantages. One is that you get more detail when you read the prototype yourself (the compiler doesn't care). So someone reading your prototypes will have a better idea of what's going on (it's customary to separate out the prototypes into a header file, and people will frequently go look through that to see what functions your code has). The other is that it's actually easier to write... just cut and paste the first line of the function, and add a ; to the end.

Technically this is optional, but I often argue that making your code readable and maintainable is just as important as making it "correct".

Quote:

---

Originally Posted by Ankheg

You're getting really close now. The only definite problem with that is that you didn't end the statement (add a ; ) and the "invoke" needs to be a comment.

---

There's another problem with it----when calling a function you don't specify its return type (that is already known).

Quote:

---

Originally Posted by Lindley

There's another problem with it----when calling a function you don't specify its return type (that is already known).

---

Hah, I didn't even see that. Good catch. :D

- Brent

Quote:

---

Originally Posted by Ankheg

Hah, I didn't even see that. Good catch. :D

- Brent

---

7. cout<<”Enter a character”;
cin>>response;
char getCharacter (); // prototype
char getCharacter (); //invoke
{
return custCode;
}


is this right?

You need to revisit the basics of function usage.

http://lmgtfy.com/?q=call+a+function+C&#37;2B%2B&l=1

You know... a lot of the issues here you would be able to solve on your own probably faster if only you installed a C++ compiler and made actual programs.

There's lots of free compilers out there, iirc there's even programs that allow you to just enter snippets of code (like the ones you need here) and that take care of all of the surrounding details on their own.