Problem with pointers of pointer ** char

Question

I have a

char** color;

I need to make a copy of the value of

*color;

Because I need to pass *color to a function but the value will be modified and I cannot have the original value to be modified.

How would you do that?

The whole code would look like this

Function1(char** color)
{
  Function2(char * color);
  return;
}

I have to mention that the pointers in function1 and 2 are used as a return value.

I take it that "Char**" should be "char**"? – andrewmu Oct 13 '10 at 13:05 — andrewmu, Oct 13 '10 at 13:05

score 1 · Accepted Answer · answered Oct 13 '10 at 13:10

1

Version 1

functionTwo( const char* color )
{
   //do what u want
}

functionOne( char** color )
{
    functionTwo( *color );
}

or version two

functionTwo( const char* color )
{
   //do what u want
}

functionOne( char** color )
{
    char* cpMyPrecious = strdup( *color );

    functionTwo( cpMyPrecious );

    free( cpMyPreciuos );
}

hth

Mario

answered Oct 13 '10 at 13:10

Mario The Spoon

4,799
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I don't think that works if I need to modify it in the function 2. – DogDog Oct 13 '10 at 13:51
Then you go with version 2, drop the const from fucntionTwo, and do not free the cpMyPresious . Use it as you think - and once you are done, free it! – Mario The Spoon Oct 13 '10 at 18:47

score 0 · Answer 2 · answered Oct 13 '10 at 13:10

0

i would suggest using strncpy() for duplicating the value. the string you are pointing at is in the memory just once, making another pointer to it doesn't solve your problem.

answered Oct 13 '10 at 13:10

Pyjong

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score 0 · Answer 3 · answered Oct 13 '10 at 13:54

Assuming you don't have strdup() available (it's not part of the standard library), you would do something like this:

#include <stdlib.h>
#include <string.h>
...
void function1(char **color)
{
  char *colorDup = malloc(strlen(*color) + 1);
  if (colorDup)
  {
    strcpy(colorDup, *color);
    function2(colorDup);
    /* 
    ** do other stuff with now-modified colorDup here
    */
    free(colorDup);
  }
}

Problem with pointers of pointer ** char

3 Answers3