I am having build errors when declaring prototype functions within Xcode. I am writing in C++. The script is pulled from my professor's lecture. Attached below is a picture of the build errors, along with the script itself.
Note: I only run into build issues when trying to declare prototype functions. It is as if Xcode is trying to pull the functions from a Library, and not recognizing it.
Code:
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
#include <cmath>
#include <cctype>
#include <cstdlib>
using namespace std;
int calcSquare (int num) ;
int main ()
{
int num = 5;
int result;
result = calcSquare(num);
cout << "The Square of " << num << " is " << result << endl;
return 0;
}
Errors: https://farm3.staticflickr.com/2871/33406384892_68ee0843c7_b.jpg
The problem with your program is that you forgot to DEFINE the function prototype later in your source code.
Right now, you simply have a function prototype ( int calcSquare ), but you called that function anyways.
That throws you the linker exception as shown.
In other words, define the function somewhere in your source code to use the <cmath>, <cctype>, <cstdlib> modules and libraries.
After the function prototype, declare the function later:
int calcSquare (int num) {
...
}
I hope this helps! :)
Related
#include <iostream>
#include <time.h>
#include <string.h>
#include <stdio.h>
int main()
{
string msg;
printf("Enter the message that you wish to display as scroller: ");
getline(cin,msg);
msg=msg+". ";
int x=0;
while(1)
{
Scroll(msg);
wait(100);
system("cls");
x++;
}
cin.get();
return 0;
}
I Have this C code and all strings in the file say 'identifier "string" is undefined'. I tried including <string> instead of <string.h> but it didn't work. Why is it not working?
Add
using namespace std;
After includes (but before main). Or, better, use notion of:
std::string // instead of string
Update: I missed the point of this being C-question. I will leave this answer, but for the sake of formality, use it if you came from Google and you are working with C++.
This is C++ code, not C.
The compiler is probably getting confused because it cannot parse it, so then it finds C-like code and all identifiers do not exist.
The includes should be:
#include <iostream>
#include <ctime>
#include <string>
#include <cstdio>
You are also missing a:
using namespace std;
Plus the definitions for Scroll and wait etc.
I started learning C++ a few weeks ago. Now I'm trying to program a kind of shop as a challenge. I've made it 2 or 3 times before, but always in one program. This time I tried to put some functions I wrote in it, so the main file wouldn't be that messed up again.
The problem I'm having is, when I'm trying to import a function, I get this error message:
E0413 There is no suitable conversion function from 'std::basic_ostream<char, std::char_traits<char>>' to 'int'.
Here's the code:
Mainfile:
#include <iostream>
#include "Benutzer.h"
using namespace std;
int main()
{
user;
}
Function:
#include <iostream>
using namespace std;
int user
{
cout << "So you're a user. What do you want to buy?"
}
I know it's not much code by now, but I was already testing.
As I can see, your program has an error in syntax.
Two things you need to consider here:
How to define a function:
return_type func_name(data_type args){
/// function body
}
How to call a function:
func_name(args);
I verified your code with little change on my system.
This is correct code:
main_file.cpp
#include <iostream>
#include "Benutzer.h"
using namespace std;
int main()
{
user();
}
Benutzer.h
#include <iostream>
using namespace std;
int user()
{
cout << "So you're a user. What do you want to buy?";
return 0;
}
This works.
I have a project that has the main method accessing another method from another source file, BigDog(int). I'm pretty sure the code is right but CodeBlocks seems to not be able to detect the definition of the method unless I build the other file using debug build in CodeBlocks. In Release, I get the following error when building:
Error: undefined reference to 'BigDog(int)'
Why is that so?
main.cpp
#include <iostream>
using namespace std;
void BigDog(int KibblesCount);
int main()
{
BigDog(3);
return 0;
}
mystuff.cpp
#include <iostream>
using namespace std;
void BigDog(int KibblesCount)
{
cout << KibblesCount;
}
If you're adding a new file in codeblocks, make sure to check the checkmarks in the dialog to add it to both the debug and the release build.
Also its better practice to move your declarations to a header file and include that where needed, like this:
main.cpp:
#include "mystuff.h"
int main()
{
BigDog(3);
return 0;
}
mystuff.h:
#pragma once
void BigDog(int KibblesCount);
mystuff.cpp:
#include "mystuff.h"
#include <iostream>
void BigDog(int KibblesCount)
{
// add a newline so the line gets printed immediately
std::cout << KibblesCount << "\n";
}
I have been trying to debug this problem for a while and quite honestly, I just can't see what I'm doing wrong.
Why is there a syntax error?
#include <iostream>;
#include <time.h>;
#include <stdio.h>;
#include <stdlib.h>;
using namespace std;
class Problem3 {
public:
bool isPrime(long double num) {
srand(time(NULL));
return 0;
}
};
The error I'm getting is,
"Function 'srand' could not be resolved."
I'm well aware now that I don't need the semi-colons after 'include' statements
I'm using Eclipse CDT along with MinGW as my compiler
How I resolved the problem:
It had to do with the MinGW compiler I was using. Switching over to Visual Studio solved the problem.
; at the end of the #include directives are the problem in your code. #include directives don't need (wrong to place indeed) semicolons at the end unlike C++ statements.
[Warning] extra tokens at end of #include directive [enabled by default]
It seems any character after > in the directive causes this error/warning.
#include<iostream>a //error
Change to this:
#include <iostream>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
class Problem3 {
public:
bool isPrime(long double num) {
srand(time(NULL));
return 0;
}
};
int main(){
cout<<"Hello Main";
}
EDIT:
Regarding the linker issue:
One suggestion is C++ expects types to be explicitly casted between types (more than C). So, use a cast to convert time_t which is returned by the time to unsigned int which is the input parameter type of srand. (And of course this might not be the problem with linker error)
Instead of using stdlib.h, try using <cstdlib>, try if it helps. Because it uses namespace.
Apart from that, I have seen this snippet here. Use that pattern if it helps.
#include <cstdlib>
#include <iostream>
#include <ctime>
using namespace std;
int main()
{
srand(time(0)); //use current time as seed for random generator
int random_variable = rand();
cout << "Random value on [0 " << RAND_MAX << "]: "
<< random_variable << '\n';
}
there is already question in SO check if that helps Eclipse Method could not be resolved in a simple program C++
Never use time() to initialize srand()..
EDIT:
Now it seems many people got this kind of problem. I found a question How do I fix Eclipse CDT Error “Function 'isdigit' could not be resolved. He is facing the same problem. The asker suggested a work around to this in his question edit.
Quoted from that question:
I now believe this to be a Code Analysis problem. A better solution is
to edit the Code Analysis options to make "Function could not be
resolved" be a warning instead of an error. That way you can see the
warnings in Problems view, but continue to work. If the function is
REALLY missing, the compiler will tell you! I also have a new theory,
that the problem is with the Code Analyzer following symlinks, because
all of the "missing" functions are in symlinked include files. Would
love any input on this theory.
Hope that points to solve the problem.
; should not be there after #include.
#include <iostream>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include files shoule not end with ;
This is really driving me crazy:
#include <iostream>
#include <vector>
#include <string.h>
#include <thread>
using namespace std;
void test() {
vector<string> myvector;
string a("Teststring");
myvector.push_back(a);
cout << myvector.begin()->length() << endl;
}
int main() {
thread(test).join();
return 0;
}
The code compiles fine with the -std=c++11 flag to the compiler and the -pthread flag to the linker.
BUT: Eclipse does either know the std::thread or the myvector.begin()->length(), even if the code runs fine eclipse warns me "Method 'length' could not be resolved".
I tried every possible solution in here: Eclipse CDT C++11/C++0x support without any success. This took me so many hours now, what am I doing wrong?!
Is there anybody getting a project setup without problems with this code?
EDIT: Other code example - same problem:
#include <iostream>
#include <vector>
#include <thread>
using namespace std;
class TestClass {
public:
void test() {
cout << "test" << endl;
}
};
void test() {
vector<TestClass> testClassVector;
TestClass x;
testClassVector.push_back(x);
testClassVector.begin()->test();
}
int main() {
thread(test).join();
return 0;
}
Compiles and runs correct, but returns in eclipse: Method 'test' could not be resolved
EDIT:
working versions:
((TestClass)*(testClassVector.begin())).test();
TestClass foo2 = *(testClassVector.begin());
foo2.test();
still not working:
testClassVector.begin()->test();
The last compiles and works like the two above, but eclipse still claims:
Method 'test' could not be resolved
Maybe I'm wrong, but I think your problem don't come from Eclypse. Juste, begin() on a vector return a std::vector<T>::iterator first, this is not a pointer and there is no method length, but you can ask for the vector size with myvector.size(); if this is what you want.
The problem could come from your #include <string.h> that is not the same as #include <string>, string.h is for string operation like strcmp, strstr, etc... juste string will define the std::string object.
I don't have Eclipse set up but the problem appears to be around std::string. Does the problem go away if you remove the threading from the example? (I also changed to #include <string> instead of string.h)
#include <iostream>
#include <vector>
#include <string>
#include <thread>
using namespace std;
#if 0
void test() {
vector<string> myvector;
string a("Teststring");
myvector.push_back(a);
cout << myvector.begin()->length() << endl;
}
#endif
int main() {
//thread(test).join();
vector<string> myvector;
string a("Teststring");
myvector.push_back(a);
cout << myvector.begin()->length() << endl;
return 0;
}
That should hopefully print out 10.
Update from comment:
Does this generate the Eclipse warning?
auto tmp = *(myvector.begin());
std::cout << tmp.length() << std::endl;
What about this?
std::string foo("abc123");
std::cout << foo.length() << std::endl;
I guess one more too:
std::string foo2 = *(myvector.begin());
std::cout << foo2.length() << std::endl;
The solution found:
I downloaded eclipse kepler Kepler
Created a new project and tried to compile this source code (like above):
#include <iostream>
#include <vector>
#include <thread>
using namespace std;
class TestClass {
public:
void test() {
cout << "test" << endl;
}
};
void test() {
vector<TestClass> testClassVector;
TestClass x;
testClassVector.push_back(x);
testClassVector.begin()->test();
}
int main() {
thread(test).join();
return 0;
}
On the first run eclipse told me, thread belongs to the new c++11 standard and I have to add -std=c++11 to the compiler flags. To use thread I also added -pthread to the linker flags. With this steps the code could be compiled, but eclipse marks the thread still as unknown. To fix this I proceeded the following step:
Under C/C++ Build (at project settings), find the Preprocessor Include Path and go to the Providers Tab. Deselect all except CDT GCC Builtin Compiler Settings. Then untag Share settings entries … . Add the option -std=c++11 to the text box called Command to get compiler specs.
Found here.
Now - unbelievable but true - it works, even without any errors marked by eclipse. The solution is using the (beta) version of eclipse, wich seems to handle this in a better way.
Thanks for all your help!