CODEWITHSUNDEEP
cfunctionpointersstructcompiler-errors
GoetheGrimm
GoetheGrimm

Reputation: 13

Cannot pass struct pointer as function argument in C

I'm trying to compile some code but I keep getting the error:

unknown type name ‘ label’;

I've declared these structures inside main, I'm not sure why I'm getting this. I'm declaring each function prototype before the main, then function declarations after main.

I think I remember doing this, shouldn't I be able to? I'm not sure how I would declare these structs earlier.

My code:

void greyScale(Image* image);
void findMaxMin(Pixel** colour,Pixel* max,Pixel* min);
void strech(Image* image);
void findEffect(Image* image,char effect[20]);

int main(int argc, char **argv)
{
    char effect[20];

    /*file i/o stuff*/

    typedef struct Pixel{
      int red;
      int green;
      int blue;
    } Pixel;

    typedef struct Imagem{
      int width;
      int height;
      Pixel **pixel;
    } Image;

    Image *image;

    /*reads files, calls functions etc..*/

    return 0;
}

void greyScale(Image* image)
{
   /*code*/
}

void findMaxMin(Pixel** colour,Pixel* max,Pixel* min);
{
   /*code*/
}    

void strech(Image* image);
{
   /*code*/
}   

void findEffect(Image* image,char effect[20]);
{
   /*code*/
}

Upvotes: 0

Views: 1253

Answers (2)

glant
glant

Reputation: 479

Check out this reference C_structures

Move you typedefs outside

typedef struct Pixel{
  int red;
  int green;
  int blue;
} Pixel;

typedef struct Imagem{
  int width;
  int height;
  Pixel **pixel;
} Image;

void greyScale(Image* image);

void findMaxMin(Pixel** colour,Pixel* max,Pixel* min);

void strech(Image* image);

void findEffect(Image* image,char effect[20]);

Upvotes: 3

dbush
dbush

Reputation: 225817

You define your structs inside of main, so they're only viewable in that function. These definitions need to be at the top level.

typedef struct Pixel{
  int red;
  int green;
  int blue;
} Pixel;

typedef struct Imagem{
  int width;
  int height;
  Pixel **pixel;
} Image;

void greyScale(Image* image);

void findMaxMin(Pixel** colour,Pixel* max,Pixel* min);

void strech(Image* image);

void findEffect(Image* image,char effect[20]);

int main(int argc, char **argv)
{
    ...
}

...

Now they're defined before they're used so they are available.

Upvotes: 0

Related Questions