How to resolve compiler warning implicit declaration of function memset

Question

My c code uses  memset  and  close   And I have added    include  lt stdio h gt   include  lt glib h gt   include  lt stdlib h gt    But I still get these warnings   main c 259  warning  implicit declaration of function    memset    main c 259  warning  incompatible implicit declaration of built-in function    memset    main c 268  warning  implicit declaration of function    close    main c 259  warning  incompatible implicit declaration of built-in function    close      Can you please tell me how can I resolve these warnings   Thank you

User · Answer

A good way to findout what header file you are missing:

 man <section> <function call>

To find out the section use:

apropos <function call>

Example:

 man 3 memset
 man 2 send

Edit in response to James Morris:

Section | Description
1 General commands
2 System calls
3 C library functions
4 Special files (usually devices, those found in /dev) and drivers
5 File formats and conventions
6 Games and screensavers
7 Miscellanea
8 System administration commands and daemons

Source: Wikipedia Man Page

User · Answer

Try to add next define at start of your  c file    define  GNU SOURCE   It helped me with pipe2 function

User · Answer

You need    include  lt string h gt     memset     include  lt unistd h gt     close      in your code   References  POSIX for close  the C standard for memset

User · Answer

memset requires you to import the header string h file  So just add the following header   include  lt string h gt

User · Answer

Old question but I had similar issue and I solved it by adding  extern void  memset void   int  size t     or just  extern void  memset      at the top of translation unit     c file

[c++] How to resolve compiler warning 'implicit declaration of function memset'

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