0x09. C - Static libraries FROMALX AFRICAprogram

General What is a static library, how does it work, how to create one, and how to use it

Basic usage of ar, ranlib, nm

Tasks

0.A library is not a luxury but one of the necessities of life

• Functions;

int _putchar(char c);  
int _islower(int c);  
int _isalpha(int c);  
int _abs(int n);  
int _isupper(int c);  
int _isdigit(int c);  
int _strlen(char *s);  
void _puts(char *s);  
char *_strcpy(char *dest, char *src);  
int _atoi(char *s);  
char *_strcat(char *dest, char *src);  
char *_strncat(char *dest, char *src, int n);  
char *_strncpy(char *dest, char *src, int n);  
int _strcmp(char *s1, char *s2);  
char *_memset(char *s, char b, unsigned int n);  
char *_memcpy(char *dest, char *src, unsigned int n);  
char *_strchr(char *s, char c);  
unsigned int _strspn(char *s, char *accept);  
char *_strpbrk(char *s, char *accept);  
char *_strstr(char *haystack, char *needle);

• Follow the step to create static library

1. First compile all .c files to get our object files .o files. gcc -c *c
2. Create a static library from our object files. ar rc libmy.a *.o
3. Check if the static library was created successfully. ar -t libmy.a
4. We confirm if our object files were linked successfully. nm libmy.a

• Compile the main code to test our static library this way: gcc -std=gnu89 main.c -L. -lmy -o quote

if you like you can execute the program ./quote

Note Create a static library

* gcc -c *.c > This converts .c files to .o (object) files  

* ar rc libmy.a *.o > This creates the static library "Libmy.a"  

* ar -t libmy.a > This lists all files in libmy.a   

1. Without libraries what have we? We have no past and no future

TOPIC

Create a script called create_static_lib.sh that creates a static library called liball.a from all the .c files that are in the current directory.

STEPS:

1. Create create_static_lib.sh file usin Vi, Vim or other text editor

2. open create_static_lib.sh and puts all following lines
   shebang > !#/bin/bash

   compile without linking files > gcc -c *.c

   create liball.a archive using all objects files > ar rc liball.a *.o

   index liball.a > ranlib liball.a

3. Exit file and type in command line chmod o+x create_static_lib.sh. this command will make create_static_lib.sh file executable for all users

4. Type ./create_static_lib.sh for final result