C Toolbox: String Processing (Page 1 of 2)

char *strset(char *s, int ch)
{ char *p;

  p = s;
  while (*p)
  { *p = ch;
    p++;
  }
  return s;
}

char *strcpy(char *dest, const char *src)
{ char *p;

  p = dest;
  while (*src)
  { *p = *src;
    p++;
    src++;
  }
  *p = 0;
  return dest;
}

char *strcat(char *dest, const char *src)
{ char *p;

  p = dest;
  while (*p)
    p++;

  while (*src)
  { *p = *src;
    p++;
    src++;
  }
  *p = 0;
  return dest;
}

int strlen(const char *s)
{
  int len;

  len = 0;
  while (*s)
  { len++;
    s++;
  }
  return len;
}

int strncmp(const char *s1, const char *s2, int n)
{ 
  while (*s1 == *s2 && n)
  { s1++;
    s2++;
    n--;
  }
  if (!n)
    return 0;
  return (*s1 - *s2);
}

char *strupr(char *s)
{
  char *p;

  p = s;
  while (*p)
  { if (*p >= 'a' && *p <= 'z')
      *p -= 0x20;
    p++;
  }
  return s;
}

char *strstr(const char *s1, const char *s2)
{
  char *p;
  int len;

  p = s1;
  len = strlen(s2);
  while (*p)
  { if (!strncmp(p, s2, len))
      return p;
    p++;
  }
  return NULL;
}

while (*b) {
    *p = *b;
    p++;
    b++;
}

#include<stdio.h>
#include<conio.h>
int main()
{
    char *p;
    char a[10];
    char *b="hallo";  /* b diubah menjadi pointer */
    clrscr();
    p=a;
    while(*b){
     *p=*b;
     b++;  /* b perlu di-increment seperti p */
     p++;
    }
    *p=0;
    printf("%s",a);  /* &a cukup ditulis a saja */
    getch();
    return 0;
}

#include<stdio.h>
#include<conio.h>
int main()
{
    char *p;
    char *q;  /* p dideklarasikan sebagai variabel bantu untuk b */
    char a[10];
    char b[]="hallo";
    clrscr();
    p=a;
    q=b;  /* q ditetapkan untuk alamat b seperti halnya p untuk a */
    while(*q){
     *p=*q;
     q++;  /* q perlu di-increment seperti p */
     p++;
    }
    *p=0;
    printf("%s",a);  /* &a cukup ditulis a saja */
    getch();
    return 0;
}

#include<stdio.h>
#include<conio.h>

int main()
{
    char *a="anak ayam";
    int i=0;
    while(*a){
     if(*a=='a'){
      i++;
     }
    a++;
    }
    printf("%d",&i);
    getch();
    return 0;
}

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

/*
 * menyisipkan 'str' ke dalam 'source' sesuai index 'idx'.
 * bila berhasil akan memberikan nilai balik berupa
 * string hasil penyisipan, bila gagal akan mengembalikan
 * nilai NULL. lakukan pemanggilan free pada string hasil
 * proses bila berhasil. lihat contoh pada fungsi main()
 */
char *insert_string (const char *source, const char *str, int idx)
{
    char      *result = NULL;
    const int src_len = strlen(source);

    if (idx > -1 && idx <= src_len && source != NULL && str != NULL) {
        int result_len = src_len + strlen(str);

        result = (char *)malloc((result_len + 1) * sizeof(char));
        if (result != NULL) {
            if (idx == 0) {
                /* di awal */
                strcat(result, str);
                strcat(result, source);
            } else if (idx == src_len) {
                /* di akhir */
                strcat(result, source);
                strcat(result, str);
            } else {
                strncat(result, source, idx);
                strcat(result, str);
                strcat(result, source + idx);
            }
        }
    }

    return(result);
}

int main (void)
{
    const char *a = "peran";
    const char *b = "coba";
    char       *c = insert_string(a, b, 3);

    if (c != NULL) {
        printf("%s\n", c);
        free(c);
        c = NULL;
    }
    c = insert_string(a, b, 0);
    if (c != NULL) {
        printf("%s\n", c);
        free(c);
        c = NULL;
    }
    c = insert_string(a, b, 5);
    if (c != NULL) {
        printf("%s\n", c);
        free(c);
        c = NULL;
    }

    return(0);
}

#include <stdio.h>

/*
 * http://www.partow.net/programming/hashfunctions/index.html
 * http://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function
 */
static unsigned int FNVHash (const char *str)
{
    const unsigned int fnv_prime = 0x811c9dc5;
    unsigned int       hash      = 0;
    unsigned int       cnt       = 0;

    while (str[cnt] != '\0') {
        hash = hash * fnv_prime;
        hash = hash ^ str[cnt];
        ++cnt;
    }

    return(hash);
}

/* strcmp dengan menggunakan hash function */
int my_strcmp (const char *s1, const char *s2)
{
    unsigned int h1 = FNVHash(s1);
    unsigned int h2 = FNVHash(s2);

    if (h2 > h1) {
        int tmp = (int)(h2 - h1);

        return(-tmp);
    }

    return(h1 - h2);
}

int main (void)
{
    printf("%d\n", my_strcmp("Beda", "beda"));

    return(0);
}