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：freewind22@163.com

*************************************/

#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);

}