Simple C++ Question [Dynamic char allocation]

I am trying to allocate new character string:

char *mystring;
mystring = new char[maxInput];

Code (markup):

When I try to send it to a function by value, it won't work:

foo(&mystring);


void foo(char *string)
{
   *string = "test";
}

Code (markup):

Error that I get is:

cannot convert `char**' to `char*' for argument `1' to `void foo(char*)

Thanks for any hints.

Peace,

 

since you have declared mystring to by a char * you do not need to use the address symbol when passing it to the foo function ... it is already a pointer type..

so you should call it like

foo(mystring);

Code (markup):

no & needed..

 

I tried the following:

foo(mystring);
void foo(char *string)
{
   *string = "test";
}

Code (markup):

Then I got an error : invalid convert from const char* to char.

So its trying to convert from a pointer to a char, which is invalid. To fix it, I did this:

foo(mystring);
void foo(char *string)
{
   string = "test";
}

Code (markup):

Which loads OK but the value of mystring isn't actually changing.

Any ideas?

Thanks again,

 

Let me ask a simpler question, it should clear things better for me:

char *myString;
myString = new char[maxSum];

Code (markup):

The first line, we create a pointer to char?
The second line is creating a dynamic char in the pointer or address?

So basically:

mystring = ? (I think the value?)
&mystring = ? (I think the address location)
*mystring = ?

Thanks,

 

Finally got it to work.. Just changed the declaration to:

void foo(char **string);

Peace,

 

myString is the address.

 

Hi,
you want to work with strings in c++ so you can define some useful functions like this.

char* CreateString(char* source)
{
int size = strlen(source); // get the length of source string
char* prov = new char[size + 1]; //allocate a buffer with exact required size
strcpy(prov, source);
prov[size] = 0; // make the string NULL terminate
return prov;
}

to call the function
char* mystring = CreateString("New string");
the variable mystring now conaines the string "New string".
hope that gonna be helpful