macOS Now There's something strange... (c++ question)

[Soulstorm]

I am stydying C++ for my exams. So, I am trying to do an exercise concerning templates . You don't need to know the question, since my question is not related to how can I do the exercise but rather a strange thing I want to verify:

My code is this:

#include <iostream>
#include <string>
using namespace std;


template<class T>
void set(T p[], int num, char *name){
	int i;
	for(i=0; i<num; i++){
		cout << name << "[" << i << "]=";
		cin >> p[i];
	}
}

template<class T>
void show(T p[], int num, char *name){
	int i;
	for(i=0; i<num; i++){
		cout << name << "[" << i << "]=" << p[i] << "\n";
	}
}

template<class T>
int greater(T a, T b){return(a>b);}
int greater(char *a, char *b){return strcmp(a,b)>0;}

template<class T>
void swap(T &a, T &b){
	T temp = a;
	a = b;
	b = temp;
}
void swap(char *a, char *b){
	char temp[20];
	strcpy(temp, a);
	strcpy(a,b);
	strcpy(b,temp);
}

template <class T>

void sort(T p[], int size){
	int i,k;
	for(k=1;k<size;k++)
		for(i=0;i<size-k;i++)
			if (greater(p[i],p[i+1])>0){
				swap(p[i],p[i+1]);
			}
}


int main(){
	char names[4][21]; int n=4;
	set(names,n,"names");
	cout<<"\nunsorted names a\n";
	show(names,n,"names");
	sort(names,n); 
	cout<<"\nsorted names\n"; 
	show(names,n,"names");
	int  numbers[4];
	set(numbers,3,"numbers"); 
	cout<<"\nunsorted numbers b\n";
	show(numbers,3,"numbers");
	sort(numbers,3);
	cout<<"\nsorted numbers\n"; 
	show(numbers,3,"numbers");
	
}

And it shows many errors in xCode. The errors have something to do with ambiguous declarations.

I change my code to this:

#include <iostream.h>
#include <string.h>


template<class T>
void set(T p[], int num, char *name){
	int i;
	for(i=0; i<num; i++){
		cout << name << "[" << i << "]=";
		cin >> p[i];
	}
}

template<class T>
void show(T p[], int num, char *name){
	int i;
	for(i=0; i<num; i++){
		cout << name << "[" << i << "]=" << p[i] << "\n";
	}
}

template<class T>
int greater(T a, T b){return(a>b);}
int greater(char *a, char *b){return strcmp(a,b)>0;}

template<class T>
void swap(T &a, T &b){
	T temp = a;
	a = b;
	b = temp;
}
void swap(char *a, char *b){
	char temp[20];
	strcpy(temp, a);
	strcpy(a,b);
	strcpy(b,temp);
}

template <class T>

void sort(T p[], int size){
	int i,k;
	for(k=1;k<size;k++)
		for(i=0;i<size-k;i++)
			if (greater(p[i],p[i+1])>0){
				swap(p[i],p[i+1]);
			}
}


int main(){
	char names[4][21]; int n=4;
	set(names,n,"names");
	cout<<"\nunsorted names a\n";
	show(names,n,"names");
	sort(names,n); 
	cout<<"\nsorted names\n"; 
	show(names,n,"names");
	int  numbers[4];
	set(numbers,3,"numbers"); 
	cout<<"\nunsorted numbers b\n";
	show(numbers,3,"numbers");
	sort(numbers,3);
	cout<<"\nsorted numbers\n"; 
	show(numbers,3,"numbers");
	
}

and it compiles fine. (Note that I have changed the headers and removed the namespace). Lastly, with a little thought, I ended up using this code:

#include <iostream>
#include <string>

using std::cout;
using std::cin;

template<class T>
void set(T p[], int num, char *name){
	int i;
	for(i=0; i<num; i++){
		cout << name << "[" << i << "]=";
		cin >> p[i];
	}
}

template<class T>
void show(T p[], int num, char *name){
	int i;
	for(i=0; i<num; i++){
		cout << name << "[" << i << "]=" << p[i] << "\n";
	}
}

template<class T>
int greater(T a, T b){return(a>b);}
int greater(char *a, char *b){return strcmp(a,b)>0;}

template<class T>
void swap(T &a, T &b){
	T temp = a;
	a = b;
	b = temp;
}
void swap(char *a, char *b){
	char temp[20];
	strcpy(temp, a);
	strcpy(a,b);
	strcpy(b,temp);
}

template <class T>

void sort(T p[], int size){
	int i,k;
	for(k=1;k<size;k++)
		for(i=0;i<size-k;i++)
			if (greater(p[i],p[i+1])>0){
				swap(p[i],p[i+1]);
			}
}


int main(){
	char names[4][21]; int n=4;
	set(names,n,"names");
	cout<<"\nunsorted names a\n";
	show(names,n,"names");
	sort(names,n); 
	cout<<"\nsorted names\n"; 
	show(names,n,"names");
	int  numbers[4];
	set(numbers,3,"numbers"); 
	cout<<"\nunsorted numbers b\n";
	show(numbers,3,"numbers");
	sort(numbers,3);
	cout<<"\nsorted numbers\n"; 
	show(numbers,3,"numbers");
	
}

(note that I included the specific statements to be used from the std namespace).

So i figured out it is a namespace problem. What are the commands that conflict with each other exactly?

Finally, do you know of any good reference to the commands each available namespace includes? I figured out that if I want to do some serious programming, I should get involved with namespaces and templates a lot, even if my exams don't require that.

 

[kainjow]

Are you compiling with GCC 4?

 

[Soulstorm]

Are you compiling with GCC 4?

yup. But it has the same problems under GCC 3.x

it doesn't matter what compiler I use. I get errors.

anyway this is a namespace problem. Do you know of any good reference on namespaces?

 

[AlmostThere]

"greater" and "swap" are both part of the standard library as is "sort" for that matter but the definitions do not clash.

Don't use "using namespace std"

Any (in fact every) c++ reference should tell you this.