Data type of pid_t is int

• /sys/types.h
• #ifndef __pid_t_defined
  typedef __pid_t pid_t;
  # define __pid_t_defined
  #endif
• bits/types.h
•  __STD_TYPE __PID_T_TYPE __pid_t;        /* Type of process identifications.  */# #define __STD_TYPE             typedef
• #define __PID_T_TYPE            __S32_TYPE
• #define __S32_TYPE              int
  

Strncmp usage from working

SYNOPSIS

#include <string.h>
 int strncmp(const char *s1, const char *s2, size_t n);

Description
The C library function int strncmp(const char *str1, const char *str2, size_t n) compares at most the first n bytes of str1 and str2.

RETURN VALUE
       The strcmp() and strncmp() functions return an integer less than, equal to, or greater than zero if s1 (or the first n bytes thereof) is found, respectively,  to  be  less  than,  to
       match, or be greater than s2.

• strncmp will be usefully only if the both strings are not null terminated, at that time only it will be useful to stop the comparison upto n.
• if we are using strlen to calculate lenght to give on  n, then strncmp is not useful.
• strncmp with strlen is as good as strcmp.
• Right way to use strncmp is to check for max allowed lenght.  we can use max size macro used to declare the string.