XORing a string in C++11

I am trying to implemnt a simple XOR encoding on a string in C++11 (Visual Studio 2017).However, I am having some problems implementing it. The following code would be my standard (C) approach:

char* encode(char*  input) {
   for (unsigned int i = 0; i < strlen(input); i++) {
        input[i] ^= 0xA; 
   }
   return(input);
 }

 int main(void){
   printf(encode(encode("Hello World!")));
 }

But it is no valid code because the string ("Hello Wolrd!") is of type const char*.

I tried several things to fix the problem:

1. Cast the string to (char*) (i.e., encode( (char*)"Hello World!")) but it throws an exception when trying to XOR the first byte.

2. Using a temp char* in my encoding function, which also resulted in stack coruption.

   char* encode(const char*  input) {
     char temp[128];
     strncpy(temp, input, 128);
     for (unsigned int i = 0; i < strlen(temp); i++) {
       temp[i] ^= 0xA;
     }
     return(temp);
    }  
   
   

3. I tried using std:string but it also did not work out.

What am I missing?