Reference to ' ' is ambiguous - c++

I am sorry but i don't know why this algorithm is not working.
The error at compiling is : "Reference to 'function' is ambiguous " and is on y = function() line, where I am calling the function
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#define PI 3.141
float function(int g, int m, int s, float z)
{
using namespace std;
z = (g + m/60.0 + s/3600.0)*PI/180.0;
return z;
}
int main()
{
using namespace std;
float y;
int g,m,s;
cout << "g = ";
cin >> g;
cout <<"m = ";
cin >> m;
cout<<"s= ";
cin >>s;
y = function();
cout << "y= " << y << endl;
//cout<< (g + m/60.0 + s/3600.0)*PI/180.0 << endl;
return 0;
}
Vers2 - updated:
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#define PI 3.141
float function(int g, int m, int s)
{
//using namespace std;
float z = (g + m/60.0 + s/3600.0)*PI/180.0;
//std::cout << z <<std::endl;
return z;
}
int main()
{
// using namespace std;
float y;
int g,m,s;
std::cout << "g = ";
std::cin >> g;
std::cout <<"m = ";
std::cin >> m;
std::cout<<"s= ";
std::cin >>s;
function();
// std::cout << "y= " << y << std::endl;
//cout<< (g + m/60.0 + s/3600.0)*PI/180.0 << endl;
return 0;
}

There is a member function in std and you inserted it into your namespace. Avoid using using namespace std;; you can import what you need this way:
using std::cout;
using std::cin;

I am getting a similar type of error while I used "prev" as a global variable of Node* type. Just renaming it with "prevv" solved issue in my case.
It is mostly due to the name of a "variable or function" is present in some library you used.

I can't reproduce your error message (for any of your versions with 3 different compilers), but the basic problem with your code is that you apparently assume the g,m,s-variables in your main functions are automatically used as parameters when you call function() just because they happen to have the same name.
This is NOT the case!
The variables inside your main and in the parameter list of function() are completely independent entities. The proper way to call the function and passing the right values is this:
y=function(g,m,s);
This basically copies the values stored inside the main g,m,s variables into the g,m,s parameters, which are accessed inside the function and after the function has completed, it then copies the value stored inside the variable you "return" from the function (here z) into the variable y.
This should work whether you are using using namespace std; or not, as your function has a completely different signature, But I'd still highly recommend to choose another name for your function.
I hope this doesn't sound like an insult, but I highly recommend that you read a introductory book about c++ programming, as it seems you are missing out on basic concepts of the language.

Related

How do you pass user input from main to other classes?

#include <iostream>
#include "multiplication.h"
#include "subtraction.h"
using namespace std;
int main() {
multiplication out;
subtraction out2;
int x, y, z;
int product;
int difference;
cout << "Enter two numbers to multiply by: ";
cin >> x;
cin >> y;
product = out.mult();
cout << "the product is: " << product;
cout << "Now enter a number to subtract the product by: ";
cin >> z;
difference = out2.sub();
cout << "the difference is: " << difference;
}
#pragma once
class multiplication
{
public:
int mult();
};
#include <iostream>
using namespace std;
#include "multiplication.h"
int multiplication::mult(int x, int y) {
return x * y;
}
#pragma once
class subtraction
{
public:
int sub();
};
#include <iostream>
using namespace std;
#include "subtraction.h"
int subtraction::sub(int product, int z) {
return product - z;
}
I need to pass the user input variables from main to mult and the user input z and product from main to sub. I tried passing them as args in the functions I've created, but they are not accessed.
Edit: I added multiplication.h and subtraction.h
In them I just have the call to the function declarations for the class.
You should pass them to the function call as arguments
difference = out2.sub(x, y);
In the .h files you should define them with arguments
class subtraction
{
public:
int sub(int x, int y);
};
Function overloading

c++ functions with math problems

I'm starting learning c++ and stepped on this problem, trying to make the following calculation: place + (place / 10)² which if place = 90 it should be 171.
#include <iostream>
#include <iomanip>
#include <cmath>
#include "TestFunction.h"
using namespace std;
int main() {
TestFunction test1 ("John", 90);
test1.getInfo();
}
here is the TestFunction header
#include <iostream>
#include <string>
#include <iomanip>
class TestFunction {
public:
TestFunction(std::string userName, int userPlace) {
name = userName;
place = userPlace;
}
int getPlace() {
return place;
}
int getResult() {
return num1;
}
void getInfo() {
std::cout << "Using getPlace():" << getPlace() << std::endl;
std::cout << "Using getResult(): " << getResult() << std::endl;
std::cout << "Using num1: " << num1 << std::endl;
std::cout << "calculate here: " << getPlace() + pow(getPlace() / 10, 2) << std::endl;
}
private:
std::string name;
int place;
int num1 = place + pow(place / 10, 2);
};
and get this result:
Using getPlace():90
Using getResult(): -2147483648
Using num1: -2147483648
calculate here: 171
I really don't know what I am missing when trying to use getResult() or num1, any advice or simple explanation will be welcome, thanks.
You need to keep track of when your calculations are done.
The init of num1 is done earlier than the initialisation of place, which is something to avoid at all cost.
You could move that calculation into the constructor:
TestFunction(std::string userName, int userPlace) {
name = userName;
place = userPlace;
num1 = place + pow(place / 10, 2);
}
There are other ways, but this is probably most accessable to you.

How to use addition in long long int?

i have write a code for addition with the variable long long but the summary is not like the normal addition
here is the code :
#include <iostream>
#include <stdlib.h>
using namespace std;
int main()
{
long long int a, b, c;
cout << "" << "";
cin >> a >> b;
c = abs(a) + abs(b);
cout << c;
cout << "\n";
}
when i input number like 1000000000000000000 2
the outpout is 1486618626 not 1000000000000000002
The old C function ::abs from <stdlib.h> takes and returns int, which cannot hold values that big on your platform.
Use std::abs from <cmath> (C++17 and later) or <cstdlib> instead.
Also, get rid of that using namespace std; and properly qualify the names instead. See Why is "using namespace std" considered bad practice?
Complete code:
#include <iostream>
#include <cstdlib>
int main() {
long long int a, b;
std::cin >> a >> b;
long long int c = std::abs(a) + std::abs(b);
std::cout << c;
std::cout << "\n";
}
Try using <cmath> instead of <stdlib.h>.
Also, don't add values while abs()ing them. Do it this way.
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
long long int a, b;
long long int c;
cin >> a >> b;
a = abs(a);
b = abs(b);
c = a + b;
cout << c;
cout << endl;
}
Code works just fine.
Input and output:
1000000000000000000 2
1000000000000000002

Compiling two projects together in Code Blocks

I'm learning C++ and tutorial asks me to add another project to what I have now.
Also I'm asked to use forward declaration so I can make use of that added file.
Here is my main project:
#include <iostream>
#include "io.cpp"
using namespace std;
int readNumber();
void writeResult(int x);
int main() {
int x = readNumber();
int y = readNumber();
writeResult(x + y);
return 0;
}
here's the added file called io.cpp:
#include <iostream>
using namespace std;
int readNumber() {
cout << "Enter a number: ";
int x;
cin >> x;
return x;
}
void writeResult(int x) {
cout << "Sum of your numbers is " << x << endl;
}
![And here's a screenshot so you can see what error I'm getting which talks about multiple definition and you can see where those two files are added.
According to the tutorial my code is okay but compiler complains. Why ?]1
In codeblocks, when creating a new class, it should automatically header file. Programming with header files is the best practice out there. Here's the code I tried and it worked, with io.h.
main.cpp
#include <iostream>
#include "io.h"
using namespace std;
io inOut;
int main()
{
int x = inOut.readNumber();
int y = inOut.readNumber();
inOut.writeResult(x + y);
return 0;
}
io.h
#ifndef IO_H
#define IO_H
class io
{
public:
int readNumber();
void writeResult(int);
};
#endif
io.cpp
#include <iostream>
#include "io.h"
using namespace std;
int io::readNumber()
{
cout << "Enter a number: ";
int x;
cin >> x;
return x;
}
void io::writeResult(int x)
{
cout << "Sum of your numbers is " << x << endl;
}
I used codeblocks to compile the code written above, and it worked perfectly.
Well as turns out when adding more cpps they're not supposed to be #included on the top. That's what makes compiler say that function is being defined multiple times. All I had to do was just get rid off that one line.
Here's my source:
http://www.cplusplus.com/forum/beginner/44651/

C++ simple class declaration program

I got a program to create in C++ in our introduction to C++ class in school. I am doing everything as I got in examples, but still getting errors.
w4x.cpp was given and I have to create Molecule.h and Molecule.cpp. I did that, but I am getting errors because my variables were not declared in scope, but I can't understand why.
// w4x.cpp
#include <iostream>
using namespace std;
#include "w4x.h"
#include "Molecule.h"
int main() {
int n = MAX_MOLECULES;
Molecule molecule[MAX_MOLECULES];
cout << "Molecular Information\n";
cout << "=====================" << endl;
for (int i = 0; i < MAX_MOLECULES; i++) {
if (!molecule[i].read()) {
n = i;
i = MAX_MOLECULES;
}
cout << endl;
}
cout << "Structure Name Mass\n";
cout << "==================================================" << endl;
for (int i = 0; i < n; i++)
molecule[i].display();
}
//Molecule.h
const int MAX_STRUCT = 10;
const int MAX_NAME = 20;
class Molecule {
char name[MAX_STRUCT];
char rate[MAX_NAME];
double weight;
public:
Molecule();
void read(const char*, const char*, double);
void display() const;
~Molecule();
};
//Molecule.cpp
#include <iostream>
#include <cstring>
using namespace std;
#include "Molecule.h"
Molecule::Molecule(){
name[0]= '\0';
rate[0]= '\0';
weight = 0;
}
void::read(const char* n, const char* r, double w) {
weight = w;
strncpy (name, n, MAX_STRUCT);
name[MAX_STRUCT]='\0';
strncpy (rate, r, MAX_NAME);
rate[MAX_NAME]='\0';
cout << "Enter structure : ";
cin.getline (n, MAX_CHARS);
cout << "Enter full name : ";
cin.getline (r, MAX_NAME);
cout << "Enter weight : ";
cin >> w;
}
void::display() const
{
int x;
for ( x=0; x<i; x++)
cout << n << " " << r << " " << w << endl;
}
My first question is, how can I pass char name[MAX_STRUCT]; char rate[MAX_NAME]; double weight; from Molecule.h to Molecule.cpp
The problem with your definitions is here:
void::read(const char* n, const char* r, double w)
and here
void::display() const
What :: says here, is that you are implementing a function within a class. So you need to specify which class and which function! What you are telling it now, is that you are implementing a function inside class void, which is nonexistent.
You should convert them to:
void Molecule::read(const char* n, const char* r, double w)
void Molecule::display() const
Your other question regarding passing class members:
The functions of a class have access to its variables, therefore, you don't need to concern yourself with that. Just use the variables.
Also, if you notice in your w4x.cpp, the function Molecule::read() is called without parameters, so your TAs ask you to implement it without parameters. Indeed, since you have access to Molecule::name, Molecule::rate and Molecule::weight directly, you should read data and write to those variables instead of asking for parameters. Therefore, your read function would look like this:
void Molecule::read()
{
// read into name, rate and weight
}
Furthermore, w4x.cpp expects read to report whether it has been successful or not. This means that you should do error checking in Molecule::read and return 0 if no errors or -1 (for example) in case of errors.