its not sorting

help please i have a program that i made its ascending and descending sorting. i used a template but its not descending can someone help me please. i know what my problem is but i dont know how to fix it. the problem is that this function fun(k,m,'d'); is not passing the parameter 'd' to the template. why is that

Code:

#include <iostream> 

using namespace std; 

template <typename mytype>

void fun2(mytype a[], int n)
{  
	int i;
	for(i=0;i<n;++i)
	  cout<<a[i]<<" ";
	cout<<endl;
}

template <typename mytype>

void fun (mytype a[], int b, char c='a')
{
    mytype temp;
    int i, j;
    
       if(c='a')
       {
          for(i=0;i<b-1;i++) 
          {                 
             for(j=i+1;j<b;j++) 
             {
                if(a[i] > a[j])    //ascending
               {
               temp=a[i];
               a[i]=a[j];
               a[j]=temp;                  
              }   
           }
        }
      }
     else if (c='d')
     {
         for(i=0;i<b-1;i++) 
         {                 
              for(j=i+1;j<b;j++) 
              { 
                if(a[i] < a[j])   //descending
                {
                temp=a[i];
                a[i]=a[j];
                a[j]=temp;                  
               }   
             }
         }
     }
   
}


int main () 
{ 
	char x='t',y='a',z='s';
	int n,m,tony,i;
	cout<<"how big do you want your array #1";
	cin>>n;
	cout<<"\nhow big do you want your array #2";
	cin>>m;
	int *u=new int[n];
	double *k=new double[m];
	cout<<"\n";
	for(i=0;i<n;i++)
	{
		cout<<"Enter the data (array 1): ";
	    cin>>u[i];
	}
	for(i=0;i<m;i++)
	{
	cout<<"Enter the data (array 2): ";
	cin>>k[i];
	}
	
	fun(u,n); 
	fun(k,m,'d'); // d is not overwriting the template. meaning is not          passing the parameter d

    fun2(u, n);
    fun2(k, m);
    

    cin.sync();
    cin.get();

          return 0; 
}

Good old = vs ==.

Code:

	if(c='a')
	{
     for(i=0;i<b-1;i++) 
     {                 
        for(j=i+1;j<b;j++) 
        {
            if(a[i] > a[j])    ascending
           {
             temp=a[i];
             a[i]=a[j];
             a[j]=temp;                  
           }   
        }
	  }
	}
	else if (c='d')

wow it work. but i dont understand why 'd' was not being pass to the function

You were not comparing c to a character. You were assigning 'a' to it which evaluates to true and the else part will never be taken.