Cout (and everything else I've attempted to put after the return) doesn't work when placed after the return in this function. What's wrong?
float tanDegrees() {
string i;
double iDouble;
string choice;
cout << "Give me a number to find the value of degrees in. ";
getline(cin, i);
iDouble = stod(i);
double PI = 3.14159265359;
float answer = tan((PI / 180)*iDouble);
cout << "Test!" << endl;
return answer;
cout << "Test!" << endl;
}
The return causes you to leave the function's scope. So anything after "return" won't be touched.
Related
I have a simple program that calculates for mpg using arrays and pointers
When I input miles, it works perfectly but when i input gallons I can only input until 5th. any advice?
At first when it was still a for loop it was until 3rd only but when i used try and catch it was until 5th
I tried changing ctr value after the first for loop where i inputted miles but it didnt change. I tried using do while and while loop and still
const int size = 10;
typedef double *pointers;
void Mperg();
void MilesPerrGallon(double *ptr1, double *ptr2);
char displayMenu(char *pt);
int main()
{
char sagot;
char *ptr;
ptr =& sagot;
displayMenu(ptr);
switch(sagot){
case '1':
Mperg();
break;
case '2':
cout << "toit";
break;
default:
cout << sagot << " is invalid";
break;
}
}
void Mperg(){
double miles[size], gallons[size];
int ctr;
pointers milPtr, galPtr;
system("cls");
cout<<"COMPUTING FOR MPG : miles per gallon...\n";
cout<<"MILES\n";
galPtr = &gallons[size];
milPtr = &miles[size];
for(ctr = 0; ctr<size; ctr++){
try{
cout << "miles[" << ctr << "]: ";
cin >> milPtr[ctr];
if(milPtr[ctr] < 100 || milPtr[ctr] > 250){
throw milPtr[ctr];
}
}
catch(double xmilPtr){
cout << milPtr[ctr] << " is invalid!.. 100-250 only\nreenter new value\n";
ctr--;
}
}
system("cls");
do{
for(ctr = 0; ctr<size; ctr++){
try{
cout << "gallons[" << ctr << "]: ";
cin >> galPtr[ctr];
if(galPtr[ctr] < 5 || galPtr[ctr] > 25){
throw galPtr[ctr];
}
}
catch(double xgalPtr){
cout << galPtr[ctr] << " is invalid!.. 5-25 only\nreenter new value\n";
ctr--;
}
}
}while(ctr<size);
}
char displayMenu(char *pt)
{
//add code here
cout << "---------O P T I O N S---------\n";
cout << "[1] Compute Miles Per Gallon" << endl;
cout << "[2] Sorting of Numbers" << endl;
cout << "[3] EXIT" << endl;
cout << "-------------------------------\n";
cout << "Enter your choice: ";
cin >> *pt;
return *pt;
}
Miles
Gallons
galPtr = &gallons[size];
milPtr = &miles[size];
Since size is 10, this:
Sets galPtr to point to the 11th element of gallons.
Set milPtr to point to the 11th element of miles.
That's what the above code means in C++.
Of course, both arrays have only ten values, and attempting to obtain a pointer and using the pointer to modify the 11th, and subsequent, values in both arrays is undefined behavior.
You obviously meant to implement galPtr=gallons and milPtr=miles, here, although there is no real reason to use pointers this way, it doesn't accomplish anything.
How do I multiply a function to another function? and how do I properly use parameters?
I'm not exactly sure, I am really new to C++ with only about 14 weeks of class time.
Something I've tried would be creating a new function meant to multiply other functions and in the arguments I would put in the functions names.
For example:
float mealMath(numberOfAdults, mealChoosing){
//Rest of function
}
but I always get an error.Please explain how to fix this, this is a big obstacle in programming for me and I can't seem to grasp how to fix this or go about doing these things. Don't be to harsh on me for this.Thanks!
int numberOfAdults(){
int totalAdults;
cout << "Now how many adults will there be?: ";
cin >> totalAdults;
cout << "It seems there will be: " << totalAdults << " Adults." << endl;
while(totalAdults < 1){
cout << "Sorry there has to be a minimum of 1 adult!" << endl;
cout << "How many adults: ";
cin >> totalAdults;
}
return 0;
}
int numberOfKids(){
int totalKids;
cout << "Now how many Kids will there be?: ";
cin >> totalKids;
cout << "It seems there will be: " << totalKids << " kids." << endl;
while(totalKids < 0){
cout << "Sorry there has to be a minimum of 1 Kid!" << endl;
cout << "How many Kids: ";
cin >> totalKids;
}
return 0;
}
float mealChoosing(){
float cost;
string mealChoise;
cout << " " << endl;
cout << "Now, What meal will you be getting(D/S): ";
cin >> mealChoise;
if(mealChoise == "D"){
cout << "It seems you have selected the Deluxe Meal plan for everyone!" << endl;
cost = 25.95;
}
if(mealChoise == "S"){
cout << "It seems you have selected the Standard Meal plan for everyone!" << endl;
cost = 21.75;
}
cout << " " << endl;
return cost;
}
One expected result is I want to multiply the input that the user gives in function "numberOfAdults" to the input a user gives for "mealChoosing"
So I want numberOfAdults * mealChoosing but I want that done in a different function so
"float total(){
float totalBill;
totalBill = numberOfAdults * mealChoosing;
cout << totalBill;"
or something along those lines. I can't complete this project because I can't for some reason properly give the functions the proper information needed in parameters.
In this case(and most) you should not declare a function whose parameters are functions. Instead declare mealMath with an integer and a float input:
float mealMath(int a, float b){/*Your code here*/}
And then later call mealMath with the other two functions passed as arguments.
float x = mealMath(numberOfAdults(), mealChoosing());
Alternatively you can have no function parameters for mealMath() and instead call numberOfAdults() and mealChoosing() from inside of the function.
It's important to note that most of the time you'll be calling a function and using its output as an argument, and therefore you'll need to put the () after the function's identifier, instead of just typing the identifier alone.
Like mealChoosing() return totalAdults and totalKids (although its not needed here) from numberOfAdults(), numberOfKids() respectively.
int numberOfAdults() {
//...
return totalAdults;
}
int numberOfKids() {
//..
return totalKids;
}
float mealChoosing() {
//..
return cost;
}
Now on mealMath(numberOfAdults, mealChoosing)
float mealMathOutput = mealMath(numberOfAdults(), mealChoosing());
I am having this problem with my calculator I made. See, when I type in a calculation it always adds a 0 to the end. I don't know how to fix this do you have any ideas?
Here's the code:
#include <iostream>
using namespace std;
void Input(float &x, float &y);
float a = 1.0, b = 1.0, result;
char op;
int main() {
cout << "Welcome to Foxy's calculator" << endl;
cout << "----------------------------" << endl;
cout << "Please input a calculation operation (eg. 1+1): ";
cin >> a >> op >> b;
Input(a, b);
cout << result << endl;
system("pause");
return 0;
}
void Input (float &x, float &y) {
a = x;
b = y;
switch (op)
{
case '+':
cout << x + y;
break;
case '-':
cout << x - y;
break;
case '*':
cout << x*y;
break;
case '/':
cout << x / y;
break;
default:
cout << "Error! Operator is not correct" << endl;
cout << "Please input your calculation with a proper operator: ";
cin >> a >> op >> b;
}
}
result is a global static variable that gets zero - initialized and is never changed. So cout << result << endl; will always print "0". To fix this you should make a, b, result and op local to main (global variables are bad), pass a, b andop to calculating function and store returned calculation result in result. It will look something like this:
float result = Input(a, b, op);
cout << result << endl;
You call cout << result << endl; in the caller. and result is always 0. This is because it is never explicitly set to anything and the C++ compiler kindly zero-initialises it since it's at global scope.
In such instances, your line by line debugger is your best friend. The fact that you've mashed up your 1) input, 2) calculation, and 3) output stages is not helping: ideally they should all be separate parts of your program.
Remove cout << result << endl;
Below you will find my dismal attempt to create a user defined function. I am trying to do an assignment that calculates the area and cost of installing carpet for various shapes. I am also suppose to keep a running total of them. In addition the assignment requires that I use a used defined function. Right now all it does is accept the input of 1 and ask "What is the length of the side: ". It then loops back to the selection menu. It does not calculate a total much less keep track of the total. What am I doing wrong in creating the user defined function and how can I incorporate it to keep a running total till they exit?
#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <cmath>
using namespace std;
void square(double);
const double UNIT_PRICE = 2.59;
const double LABOR_COST = 32.5;
const double PIE = 3.14;
const double TAX = .0825;
int main() {
int selection;
int sqrSide = 0;
// declare and initialize the variables for the shape
int sqrTot = 0;
do {
// get input from user as to what they want to do
cout << "Carpet Area Shape" << endl;
cout << "1. Square" << endl;
cout << "2. Rectangle" << endl;
cout << "3. Circle" << endl;
cout << "4. Triangle" << endl;
cout << "5. Done" << endl;
cout << "Type a number to continue: ";
cin >> selection;
cout << endl;
// loop through the solutions based on the user's selection
switch (selection) {
case 1:
cout << "What is the length of the side: ";
cin >> sqrSide;
square(sqrSide);
if (sqrTot > 0) {
cout << "Shape: Square" << endl;
cout << "Side: " << sqrSide << endl;
cout << "Area: " << sqrTot << endl;
}
cout << endl;
system("pause");
break;
case 2:
case 3:
case 4:
case 5: // exit
system("cls");
break;
default:
"You have made an invalid selection. Please choose a number from the "
"list.";
cout << endl;
}
// loop through if the user is still making a valid selection
} while (selection != 5);
system("pause");
return 0;
}
void square(double) {
double sqrSide = 0;
double sqrTot = 0;
double sqrArea;
sqrArea = sqrSide * 4;
// get the total area and store it as a variable
sqrTot += sqrArea;
if (sqrTot > 0) {
cout << "Shape: Square" << endl;
cout << "Side: " << sqrSide << endl;
cout << "Area: " << sqrTot << endl;
}
}
When you declare the prototype of the function you can omit the parameter but in the implementation you must place it.
change:
void square(double)
{
double sqrSide = 0;
double sqrTot = 0;
double sqrArea;
sqrArea = sqrSide * 4;
//get the total area and store it as a variable
sqrTot += sqrArea;
if (sqrTot > 0) {
cout << "Shape: Square" << endl;
cout << "Side: " << sqrSide << endl;
cout << "Area: " << sqrTot << endl;
}
}
to:
void square(double sqrSide)
{
double sqrTot = 0;
double sqrArea;
sqrArea = sqrSide * 4;
//get the total area and store it as a variable
sqrTot += sqrArea;
if (sqrTot > 0) {
cout << "Shape: Square" << endl;
cout << "Side: " << sqrSide << endl;
cout << "Area: " << sqrTot << endl;
}
}
and also change:
case 1:
cout << "What is the length of the side: ";
cin >> sqrSide;
square(sqrSide);
if (sqrTot > 0) {
cout << "Shape: Square" << endl;
cout << "Side: " << sqrSide << endl;
cout << "Area: " << sqrTot << endl;
}
cout << endl;
system("pause");
break;
to:
case 1:
cout << "What is the length of the side: ";
cin >> sqrSide;
square(sqrSide);
system("pause");
break;
As mentioned by πάνταῥεῖ in a comment, it seems that you've a few misconceptions regarding scope of variables, about parameters and about return values. Let's see if we can't dispel some of those.
First of all, lets talk about scope. When we declare a variable inside a block delimited with { and }, the variable only exists inside that block. Code that follows the block cannot access the variable.
So, this is okay:
int a = 3;
int b = 2;
int c = a*b;
But, this is not, since the values of a and b are no longer available:
{
int a = 3;
int b = 2;
}
int c = a*b;
Next, lets talk about parameters. These are the inputs to functions which the function will use in order to complete its task. While their name is irrelevant and essentially meaningless, it will certainly help you and others of you give them meaningful names. Some programming languages and indeed, students of some disciplines don't follow this maxim and can produce code that's harder to follow than it need be. The implementation of Basic found in 20 year old Texas Instruments calculators and physicists, I'm looking at you!
Consider the following functions, (whose bodies I've ommitted for brevity):
double calcArea(double a)
{
...
}
double calcArea(double b)
{
...
}
They both suck. What's a stand for, how about b?
A far better pair might resemble:
double calcArea(double radius)
{
...
}
double calcArea(double sideLenOfSquare)
{
...
}
Lastly, lets talk about return values. In each of the 4 preceding functions, the declaration begins with double. This means that we can expect to get back a value of type double from the function. However, this is just coding - there's no magic and as such, we need to actually let the compiler know what this value will be. Extending the two previous functions, we might come up with some something like the following:
double calcArea(double radius)
{
return 3.1415926535 * (radius * radius);
}
double calcArea(double sideLenOfSquare)
{
return sideLenOfSquare * sideLenOfSquare;
}
Now as it turns out - even these two simple functions are not all they've cracked-up to be. Namely, the first function uses a constant - π (Pi or 3.141....) This already exists (and with far better precision than I've used) in the math.h header file. If this file is included, we then have access to the #defined constant, M_PI.
Next, both of these functions have the same name and take the same number of parameters of identical type. The compiler can't possibly know which one you'd like to invoke. At a minimum, they should have different names. Perhaps something like calcCircleArea and calcSquareArea. Now, the compiler knows which function you're referring to and will happily compile this part of the code. Errors may exist elsewhere, but these are a different matter.
A little research on function overloading will provide resources that can explain the problem and solution to functions with the same name far better than I am both able and inclined to try. :)
I'm working on a currency converter program that converts the old system of British pounds, Shillings, and pence, into their new system, which is a type of Decimal Pound. Where 100 pence equals a pound. Here is the code for the program
#include <iostream>
#include <iomanip>
#include <conio.h>
using namespace std;
int calcNum(int pound, int shilling, int pence)
{
pence = pound*240 + shilling*12 + pence;
return pence;
}
int calcNew(int total_pence, double dec_pound)
{
dec_pound = total_pence / 240;
return dec_pound;
}
int main()
{
int pence;
int shilling;
int pound;
const int OLD_POUND = 240;
const int OLD_SHILLING = 12;
double total_pence;
double dec_pound = 0;
double deci_pound;
cout << "Please Enter the Amount of old pounds: ";
cin >> pound;
cout << endl;
if(cin.fail())
{
cout << "That's not a valid number\n";
cout << "This program will terminate on any keypress!";
_getch();
exit(1);
}
cout << "Please Enter the Amount of old shillings: ";
cin >> shilling;
cout << endl;
if(cin.fail())
{
cout << "That's not a valid number\n";
cout << "This program will terminate on any keypress!";
_getch();
exit(1);
}
cout << "Please Enter the Amount of old pence: ";
cin >> pence;
cout << endl;
if(cin.fail())
{
cout << "That's not a valid number\n";
cout << "This program will terminate on any keypress!";
_getch();
exit(1);
}
total_pence = calcNum(pence, shilling, pound);
deci_pound = calcNew(dec_pound, total_pence);
cout << (5, "\n");
cout << "The total amount in decimal pounds is: ";
cout << setprecision(2) << "\x9c" << deci_pound;
_getch();
return 0;
}
When I run this program however, I'm having a bit of a problem. No matter what the number input is, it always says 0 pounds. Just to make sure that the setprecision function at the end wasn't interfering with the code, I had originally set a cout statement with a _getch() after the two functions to show how much deci_pound came out to be calculated to, and once again, it came out as zero. So my issue seems to be somewhere in the functions running the calculations. If someone could help me with this, I would really appreciate it.
Your calcNew(...) function returns an int, make it return a double. Right now it casts to int which involves stripping the decimals.
In your code, dec_pound is set equal to zero, and you're deci_pound = calcNew(dec_pound, total_pence), which divides 0 by 240 = 0.
The order of the parameters when you call both functions is wrong. Your functions are declared and implemented as:
int calcNum(int pound, int shilling, int pence);
int calcNew(int total_pence, double dec_pound);
And then you call them like this:
total_pence = calcNum(pence, shilling, pound);
deci_pound = calcNew(dec_pound, total_pence);