memccpy
#include <stdio.h>
#include <string.h>

int main (int argc, char *argv[])
{
    char src[] = "One, Two, Three, Four, Five";
    char buff[256];
    char *dest;
    puts(src);
    puts(""); //  new line


    //  copy into buff src to first 'F' char

    dest = memccpy(buff,src,'F',strlen(src));
    *dest = '\0';

    printf("dest : %s\n",dest);
    printf("buff : %s\n",buff);
    
    return 0;
}
OUTPUT :
//  One, Two, Three, Four, Five
//
//  dest :
//  buff : One, Two, Three, F

memchr
#include <stdio.h>
#include <string.h>

int main (int argc, char *argv[])
{
    char *str = "aaaAbbbAcccAddd";
    int ch = 'A';
    char *ptr;

    printf("str : %s\n",str);
    printf("ch  : %c\n",ch);

    ptr = memrchr(str,ch,strlen(str));
    printf("pointer to first %c : %s\n",
        (char)ch,ptr);
            
    return 0;
}
OUTPUT :
//  str : aaaAbbbAcccAddd
//  ch  : A
//  pointer to first A : AbbbAcccAddd

memcmp
#include <stdio.h>
#include <string.h>

int main (int argc, char *argv[])
{
    char buff1[] = "First String";
    char buff2[] = "First string";
    size_t cmp;

    puts(buff1);
    puts(buff2);
    puts(""); //  new line


    cmp = memcmp(buff1,"First str",5);

    if ( cmp == 0 )
        puts("first 5 char buff1 and string are equal");
    else if ( cmp < 0 )
        puts("buff1 is less then string");
    else
        puts("buff1 is greater then string");

    cmp = memcmp(buff1,buff2,strlen(buff1));

    printf("cmp = %d\n",cmp);

    if ( cmp == 0 )
        puts("first 5 char buff1 and buff2 are equal");
    else if ( cmp < 0 )
        puts("buff1 is less then buff2");
    else
        puts("buff1 is greater then buff2");
        
    return 0;
}
OUTPUT :
//  First String
//  First string
//
//  first 5 char buff1 and string are equal
//  cmp = -1
//  buff1 is greater then buff2

memcpy
#include <stdio.h>
#include <string.h>

int main (int argc, char *argv[])
{
    char *str = "One, Two, Three, Four, Five";
    char buff1[256] = "\0";
    char buff2[] = "aaaaaaaaaaaaaaaaaaaaaaaaaa";
    puts(str);
    puts(buff2);
    puts(""); //  new line


    memcpy(buff1,str+5,10);
    puts(buff1);
    printf("Length of buff1 is %d\n",strlen(buff1));
    
    memcpy(buff2+5,str+9,8);
    puts(buff2);
    printf("Length of buff2 is %d\n",strlen(buff2));

    /* overlapping of the buff2 */
    /* use memmove instead */
    memcpy(buff2+5,str,strlen(str));
    puts(buff2);
    printf("Length of buff2 is %d\n",strlen(buff2));

    return 0;
}
//  One, Two, Three, Four, Five
//  aaaaaaaaaaaaaaaaaaaaaaaaaa
// 
//  Two, Three
//  Length of buff1 is 10
//  aaaaa Three, aaaaaaaaaaaaa
//  Length of buff2 is 26
//  aaaaaOne, Two, Three, Four, Five Three
//  Length of buff2 is 38

memmem
#define _GNU_SOURCE
#include <stdio.h>

int main (int argc, char *argv[])
{
    char src[]     = "first and last line";
    char pattern[] = "line";
    char *ptr;
    
    printf("src     : %s\n",src);
    printf("pattern : %s\n",pattern);
    puts(pattern);
    
    ptr = (char*)memmem(src,strlen(src),
            pattern,strlen(pattern));

    printf("pointer to pattern : %s\n",ptr);

    return 0;
}
OUTPUT :
//  this function consists bug
//  and is dangerous to use
// 
//  src     : first and last line
//  pattern : line
//  line
//  pointer to pattern : line

memmove
#include <stdio.h>
#include <string.h>

int main (int argc, char *argv[])
{
    char *str = "One, Two, Three, Four, Five";
    char buff[256] = "aaaaaaaaaaaaaaaaaaaaaaaaaa";
    puts(str);
    puts(buff);
    puts(""); //  new line


    memcpy(buff,str+5,12);
    puts(buff);
    printf("Length of buff is %d\n",strlen(buff));
    
    /* overlapping of the buff    */
    /* memcpy does it not correct */
    memmove(buff+10,str,strlen(str));
    puts(buff);
    printf("Length of buff is %d\n",strlen(buff));

    return 0;
}
//  One, Two, Three, Four, Five
//  aaaaaaaaaaaaaaaaaaaaaaaaaa
//
//  Two, Three, aaaaaaaaaaaaaa
//  Length of buff is 26
//  Two, ThreeOne, Two, Three, Four, Five
//  Length of buff is 37

memrchr
#include <stdio.h>

int main (int argc, char *argv[])
{
     char *str = "aaaAbbbAcccAddd";
     char *ptr;
     int ch = 'A';

     /* last occurrence of 'A' into str */
     ptr = (char*)memrchr(str,ch,strlen(str));

     puts(ptr);

     return 0;
}
OUTPUT :
//  Addd

memset
#include <stdio.h>
#include <string.h>

int main (int argc, char *argv[])
{
    char buff1[] = "One, Two, Three, Four, Five";
    char buff2[256];
    puts(buff1);
    puts(""); //  new line


    memset(buff1,'-', 9);
    puts(buff1);
    memset(buff1+17, '-',10);
    puts(buff1);
    puts("");

    memset(buff2,'*',27);
    memset(buff2+27,'\0',1);
    puts(buff2);

    return 0;
}
OUTPUT :
//  One, Two, Three, Four, Five
//
//  --------- Three, Four, Five
//  --------- Three, ----------
//
//  ***************************