pointer magic

[mohit dhawan]

void change(char *s)
{
        s="change";
}

int main()
{
        char *p="abc";
        change(p);
        cout<<p;
        return 0;
&#125;

according 2 me the ouput should be change but the outoput is abc
any reasons why

[lakerdonald]

try making it:

strcpy(s, "change");

You'll have to include string.h

[burnit]

All function arguments are passed by value: the value of the argument is copied.

In the routine change, you don't modify the variable p declared in main, but its copy used as argument in the function chage... To modify variables you should use pointers, but because a" string" is just like a pointer, you must use a double pointer.

A solution can be...

[code]
void change(char **s) /* double pointer! */
{
s="change";
}

int main()
{
char *p="abc";
change(&p); /* we must pass a char** */
cout<<p; /* Now prints "change" */
return 0;
}
&#91;code&#93;&#91;/code&#93;

[lakerdonald]

True. I would have just passed the function a pointer anyway.

[Roxoff]

And (seeing as how you're using C++) you can do this with a reference too!