some string manipulation functions in C

  1: #include <stdio.h>
  2: #include <string.h>
  3: 
  4: char* my_strcpy(char* dest,const char* src);
  5: char* my_strncpy(char* dest,const char* src, size_t num);
  6: char* my_strcat(char* dest,const char* src);
  7: char* my_strncat(char* dest,const char* src,size_t num);
  8: int my_strcmp(const char* str1, const char* str2);
  9: int my_strncmp(const char* str1, const char* str2, size_t num);
 10: 
 11: main()
 12: {
 13:  
 14:  char arr1[] = "mithun";
 15:  char arr2[] = "my name is mithun";
 16:  char arr3[40] = "";
 17:  char* temp = arr3;
 18:  printf("%s \n",my_strncpy(arr1,arr2,6)?arr1:"dest size not adequate");  
 19:  printf("%s \n",my_strncpy(arr2,arr2,6)?arr2:"dest size not adequate");
 20:  printf("%s \n",arr2);  
 21:  printf("%s \n",my_strncpy(arr1,arr2,7)?arr1:"dest size not adequate");  
 22:  printf("%s \n",arr1);
 23:  
 24:  while(*temp)
 25:  printf("%p %c \n",temp,*temp++);
 26:  printf("%p --> %c \n",temp,*temp);
 27:   
 28:  printf("%s \n",my_strcat(arr3,arr1));  
 29:  printf("%s \n",my_strcat(arr3," hi to all of you"));
 30:  printf("%s \n",my_strncat(arr3," again hello, milo, bolo to all of you",7));
 31:  printf("%s \n",my_strncat(arr3,"you",6));
 32:  printf("%d \n",my_strcmp("abc","abc")); 
 33:  printf("%d \n",my_strcmp("abc","abcd")); 
 34:  printf("%d \n",my_strcmp("abcd","abc"));
 35:  printf("%d \n",my_strcmp("abc","xyz"));
 36:  printf("%d \n",my_strcmp("abc","abz"));
 37:  printf("%d \n",my_strcmp("a","a"));    
 38:  
 39:  printf("%d \n",my_strncmp("abc","axc",2)); 
 40:  printf("%d \n",my_strncmp("abc","abc",3)); 
 41:  printf("%d \n",my_strncmp("abc","abc",6));
 42:  
 43:  getchar();
 44: }
 45: 
 46: int my_strncmp(const char* str1, const char* str2,size_t num)
 47: {
 48:  while(*str1++ == *str2++ && num--)
 49:  {
 50:    if(!(*str1) && !(*str2) || !num)//both reached to NULL
 51:     return 0;  
 52:  }
 53:   str1--;
 54:   str2--;
 55:   if(*str1 > *str2)
 56:    return 1;
 57:   else if(*str1 < *str2)
 58:    return -1;  
 59: }
 60: 
 61: int my_strcmp(const char* str1, const char* str2)
 62: {
 63:  while(*str1++ == *str2++)
 64:  {
 65:    if(!(*str1) && !(*str2))//both reached to NULL
 66:     return 0;  
 67:  }
 68:   str1--;
 69:   str2--;
 70:   if(*str1 > *str2)
 71:    return 1;
 72:   else if(*str1 < *str2)
 73:    return -1;
 74: }
 75: 
 76: char* my_strcat(char* dest,const char* src)
 77: {
 78:  char* temp = dest;
 79:  while(*dest != '\0'){dest++;}
 80:  while(*dest++ = *src++);
 81:  return temp;
 82: 
 83: }
 84: 
 85: char* my_strncat(char* dest,const char* src,size_t num)
 86: {
 87:  char* temp = dest;
 88:  while(*dest != '\0'){dest++;}
 89:  
 90:  while(num-- && *src)
 91:   *dest++ = *src++;
 92:   *dest = '\0';
 93: 
 94:  return temp;
 95: 
 96: }
 97: 
 98: char* my_strncpy(char* dest,const char* src, size_t num)
 99: {
100:  if(dest == src)
101:   return NULL;
102: 
103:  char* temp = dest;
104:  while(num--)
105:   {
106:    if(*dest == '\0')
107:     return NULL;
108:    *dest++ = *src++;
109:   }
110:  return temp;
111: }
112: 
113: char* my_strcpy(char* dest,const char* src)
114: {
115:  char *temp = dest;
116:  while(*dest++ = *src++);
117:  return temp;  
118: }
119: