c++ assign char values (by using stack pop) to char*

Question

I am trying to reverse a char* by using a stack.

stack<char> scrabble;
char* str = "apple";

while(*str)
{
    scrabble.push(*str);
    str++;
    count++;
}

while(!scrabble.empty())
{
     // *str = scrabble.top();
     // str++;
     scrabble.pop();
}

In the second While-loop, I'm not sure how to assign each char from the stack's top to the char* str.

Shouldn't you just iterate over it backwards and copy it into a new buffer? — , Nov 05 '15 at 05:34

score 7 · Accepted Answer · answered Nov 05 '15 at 05:29

When you have a string defined using
```
char* str = "apple";
```
you are not supposed to change the value of the string. Changing such a string causes undefined behavior. Instead, use:
```
char str[] = "apple";
```

In the while loops, use an index to access the array instead of incrementing str.

int i = 0;
while(str[i])
{
    scrabble.push(str[i]);
    i++;
    count++;
}

i = 0;
while(!scrabble.empty())
{
   str[i] = scrabble.top();
   i++;
   scrabble.pop();
}

Thanks for reminding me of that "apple" is a const char[]. – coffeefirst Nov 05 '15 at 06:09 — coffeefirst, Nov 05 '15 at 06:09

score 2 · Answer 2 · answered Nov 05 '15 at 05:38

You can also iterate a pointer to the char[] if you'd like

char str[] = "apple";

char* str_p = str;
int count = 0;

while(*str_p)
{
    scrabble.push(*str_p);
    str_p++;
    count++;
}

// Set str_p back to the beginning of the allocated char[]
str_p = str;

while(!scrabble.empty())
{
     *str_p = scrabble.top();
     str_p++;
     scrabble.pop();
}

c++ assign char values (by using stack pop) to char*

2 Answers2