Question

I need to compile some code originally written in C++ in C for a specific platform. I am having problem with the line below which is attempting to set p to the start of outputdata as below.

I am getting a compiler error error C2143: syntax error : missing ‘;’ before ‘type’

How do I need to change this to compile in C?

size_t example_function(unsigned char** outputdata, size_t *output_length)
{
   *outputdata = (unsigned char*)malloc(20);

   unsigned char* p = *outputdata;

   return 0;
}

Answer 1

I’m guessing that you are using the Visual C++ compiler to compile this. This compiler only supports C90 (aka C89), so you will need to put declarations before any other statements in any block.

size_t example_function(unsigned char** outputdata, size_t *output_length)
{
    unsigned char* p;

    *outputdata = malloc(20);

    p = *outputdata;

    return 0;
}

I am assuming that you have (directly or indirectly) included <stdlib.h> for definitions of size_t and malloc otherwise you would probably have a different error.