C语言字符串操作函数

/************************************
名 称：CString
作 者：freewind
版 本：v1.0
时 间：2006-08
Email：[e-mail]
*************************************/

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

#define TRUE 1
#define FALSE 0

/************************************ StrLength **********************************/
int StrLength( const char *str )
{
 int len;
 for( len=0; *str++; len++ );
 return len;
}
/************************************ StrAssgin **********************************/
char *StrAssign( char *dest, const char *sour )
{
 int len;
 char *ret;
 len=StrLength( sour );
 ret=dest=(char *)malloc(len+1);
 if( !dest )
  printf("内存分配失败!/n");
 else
  while( *dest++ = *sour++ );
 return ret;
}
/************************************ StrCopy **********************************/
char *StrCopy( char *dest, const char *sour )
{
 char *ret=dest;
 if( !dest || !sour )
  printf("源串或目标串为空!/n");
 else
  while( *dest++ = *sour++ );
 return ret;
}
/************************************ StrEmpty **********************************/
int StrEmpty( const char *str )
{
 if( str )
  return *str?FALSE:TRUE;
 else
  return TRUE;
}
/************************************ StrCompare *******************************/
int StrCompare( const char *str1, const char *str2 )
{
 int result=0;
 if( str1!=str2 )
  while( (*str1 || *str2) && !(result=*str1++ - *str2++) );
 return result;
}
/************************************ StrConcat ********************************/
char *StrConcat( char *dest, const char *sour )
{
 char *ret=dest;
 while( *dest ) dest++;
 while( *dest++ = *sour++ );
 return ret;
}
/************************************ SubString *********************************/
char *SubString( char *dest, const char *sour, int start, int len )
{
 char *ret=dest;
 int i;
 for(i=0; i<start && *sour++; i++);
 for(i=0; i<len && *sour; i++)
  *dest++ = *sour++;
 *dest=0;
 return ret;
}
/************************************ StrIndex *********************************/
int StrIndex( const char *str, const char *substr, int start )
{
 int i, j, result=-1;
 
 for( i=start,j=0; str[i] && substr[j]; i++,j++ )
 {
  if( str[i] !=substr[j] )
  {
   start++;
   i=start;
   j=0;
  }
 }
 if( !substr[j] )
  result=start;
 return result;
}
/************************************ StrReplace **********************************/
int StrReplace( char *str, const char *rep, const char *des )
{
 int pos=0, len1, len2;
 int i, c, count=0;
 char *p,*q;

 pos=StrIndex( str, rep, pos );
 len1=StrLength( rep );
 len2=StrLength( des );
 c=len1-len2;

 while( pos>=0 )
 {
  p=&str[pos+len2];
  if( len1 > len2 ) /* <-- */
  {      
   while( *p=*(p+c) )
   {
    p++;
   }
    
  }
  else if( len1 < len2 ) /* --> */
  { 
   c=-c;
   q=&str[StrLength( str )+c];
   while( q>=p )
   {
    *q=*(q-c);
    q--;
   }
  }
  /*replace */
  count++;
  p=&str[pos];
  /*printf("%s/n/n", p );*/
  for(i=0;i<len2;i++)
   *p++=des[i];
  
  pos+=len2+1;
  pos=StrIndex( str, rep, pos );
 }
 return count;
}
/************************************ StrInsert **********************************/
void StrInsert( char *str, int pos, const char *instr )
{
 int len;
 char *p,*q;

 len=StrLength( instr );
 p=&str[pos];
 q=&str[StrLength( str ) + len];
 while( q>=p )
 {
  *q=*(q-len);
  q--;
 }
 while( *instr )
  *p++=*instr++;

}
/************************************ StrDelete **********************************/
void StrDelete( char *str, int pos, int len )
{
 char *p;
 p=&str[pos];

 while( *p=*(p+len) )
  p++;

}
/************************************** main ***********************************/
void main()
{
 char str[50]="I am a student";
 char s1[20]="abd",s2[20]="abcd",s3[]="abcde",s4[]="abcd";
 char str2[20];
 char *s=0;
 const char *ss;
 int index;

 printf("-----------------StrCopy  StrEmpty  StrLength ---------------/n");
 StrCopy( str2, str );
 printf("%s /n%s /n%d %d/n",str,str2,StrLength(str), StrLength(str2));
 printf("%d  %d /n",StrEmpty(s),StrEmpty(str) );

 printf("--------------------StrCompare StrAssign ------------------/n");
 printf("%s %s %s %s/n",s1,s2,s3,s4);
 printf("%d %d %d %d/n",StrCompare(s1,s2),StrCompare(s2,s3),StrCompare(s1,s3),StrCompare(s2,s4));
 s=StrAssign( s,str+2 );
 printf("%s /n%d /n",s,StrLength(s) );
 
 printf("--------------------StrConcat SubString -------------------/n");
 StrConcat( s1, s2 );
 printf("s1+s2=%s/n",s1 );
 SubString(s1,str,5,10);
 ss=SubString(s2,str,0,20);
 printf("%s  %s/n",s1,s2);

 printf("----------------------StrIndex StrReplace -------------------/n");
 index=StrIndex( str, "am", 0 );
 printf("%d %d  %d/n", index, StrIndex( str, "Kk", 0 ), StrIndex( "ababab","ab",1 ) );
 printf("%s/n", str );
 index=StrReplace( str, "am", "are" );
 printf("%d %s ",index, str );
 index=StrReplace( str, "are", "am" );
 printf("%d %s ",index, str );
 index=StrReplace( str, "am", "AM" );
 printf("%d %s /n",index, str );

 printf("----------------------StrInsert StrDelete --------------------/n");
 StrInsert( str, 4, " not" );
 printf("%s ", str );
 StrDelete( str, 4, 4 );
 printf("%s /n", str );

 free(s);
}