mixed declarations and codes

Question

When I compile function with \"gcc -o dene -Wall -ansi -pedantic-errors dene.c\" ,gcc emits no error.(can you look a line which starts with char ....,in if loop,)

Answer 1

In K&R and ANSI c, you must always put declarations at the start of a scope block. This requirement is relaxed in c99.

So, whats a scope block? A region delimited by { and }.

So in you above example the declaration

{
   char *p=malloc(sizeof(char)*3); /* ...

is OK because it occurs immediately after a {, while

{
  char **cmainp=malloc(sizeof(char*)*1);    

  /*look*/ cmainp[0]=malloc(sizeof(char)*300); /*look*/

  int len=0;...

fails because the assigment comes between the { and the second declaration (int len=0;).