C语言去除相邻重复字符函数的实现方法
C语言去除相邻重复字符函数的实现方法
字符去重函数
功能：去重字符串相邻重复的字符，不相邻的不用去重
参数：
arg1--输入字符串
arg2--字符串开始位置
arg3--字符串结束位置
要求：
输入参数为arg1时，对这个字符串去重
输入参数为arg1，arg2时，从arg2位置到字符串结束，去重
输入参数为arg1，arg2，arg3时，从arg2到arg3位置，去重
src/include/catalog/pg_proc.h
DATA(insertOID=6669(remove_dup_charPGNSPPGUID121000fffftfi1025"25"_null__null__null__null__null_remove_dup_char_arg1_null__null__null_));
DESCR("Removeduplicatecharacters.");
DATA(insertOID=6670(remove_dup_charPGNSPPGUID121000fffftfi2025"2523"_null__null__null__null__null_remove_dup_char_arg2_null__null__null_));
DESCR("Removeduplicatecharacters.");
DATA(insertOID=6671(remove_dup_charPGNSPPGUID121000fffftfi3025"252323"_null__null__null__null__null_remove_dup_char_arg3_null__null__null_));
DESCR("Removeduplicatecharacters.");
src/backend/utils/adt/myfuncs.c
/*
*Removeduplicatecharacters
*author:young
*/
Datum
remove_dup_char_arg1(PG_FUNCTION_ARGS)
{
intn=0;
text*arg0=PG_GETARG_TEXT_P(0);
char*str=text_to_cstring(arg0);
n=strlen(str);
remove_dup(str,0,n);
PG_RETURN_TEXT_P(cstring_to_text(str));
}
Datum
remove_dup_char_arg2(PG_FUNCTION_ARGS)
{
intn=0;
text*arg0=PG_GETARG_TEXT_P(0);
int32arg1=PG_GETARG_INT32(1);
char*str=text_to_cstring(arg0);
n=strlen(str);
if(!(1<=arg1&&arg1<=n))
{
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("outofrange")));
}
remove_dup(str,arg1-1,n);
PG_RETURN_TEXT_P(cstring_to_text(str));
}
Datum
remove_dup_char_arg3(PG_FUNCTION_ARGS)
{
intn=0;
text*arg0=PG_GETARG_TEXT_P(0);
int32arg1=PG_GETARG_INT32(1);
int32arg2=PG_GETARG_INT32(2);
char*str=text_to_cstring(arg0);
n=strlen(str);
if(!(1<=arg1&&arg1<=arg2&&arg2<=n))
{
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("outofrange")));
}
remove_dup(str,arg1-1,arg2-1);
PG_RETURN_TEXT_P(cstring_to_text(str));
}
void
remove_dup(char*str,intstart,intend)
{
inti=start,k=start;
for(i=start;i<=end;i++)
{
if(str[i+1]&&str[i+1]==str[i]&&i+1<=end)
{
k++;
}
else
{
str[i-k]=str[i];
}
}
str[i-k]='\0';
}
比较繁琐，再做一下修改，三个函数放到一个中
src/include/catalog/pg_proc.h
DATA(insertOID=6669(remove_dup_charPGNSPPGUID121000fffftfi1025"25"_null__null__null__null__null_remove_dup_char_null__null__null_));
DESCR("Removeduplicatecharacters.");
DATA(insertOID=6670(remove_dup_charPGNSPPGUID121000fffftfi2025"2523"_null__null__null__null__null_remove_dup_char_null__null__null_));
DESCR("Removeduplicatecharacters.");
DATA(insertOID=6671(remove_dup_charPGNSPPGUID121000fffftfi3025"252323"_null__null__null__null__null_remove_dup_char_null__null__null_));
DESCR("Removeduplicatecharacters.");
src/backend/utils/adt/myfuncs.c
添加定义：
#definePG_GETARG_IF_EXISTS(n,type,defval)\ ((PG_NARGS()>(n)&&!PG_ARGISNULL(n))?PG_GETARG_##type(n):(defval))
修改方法：
/*
*Removeduplicatecharacters
*author:yangjie
*/
Datum
remove_dup_char(PG_FUNCTION_ARGS)
{
text*arg0=PG_GETARG_IF_EXISTS(0,TEXT_P,NULL);
int32arg1=PG_GETARG_IF_EXISTS(1,INT32,0);
int32arg2=PG_GETARG_IF_EXISTS(2,INT32,0);
intn=0;
char*str=text_to_cstring(arg0);
n=strlen(str);
if(PG_NARGS()==1)
{
remove_dup(str,0,n);
}
if(PG_NARGS()==2)
{
if(!(1<=arg1&&arg1<=n))
{
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("outofrange")));
}
remove_dup(str,arg1-1,n);
}
if(PG_NARGS()==3)
{
if(!(1<=arg1&&arg1<=arg2&&arg2<=n))
{
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("outofrange")));
}
remove_dup(str,arg1-1,arg2-1);
}
PG_RETURN_TEXT_P(cstring_to_text(str));
}
再修改一下，如果有输入参数就用没有就用默认值 最后再去重处理减少代码重用
/*
*Removeduplicatecharacters
*author:yangjie
*/
Datum
remove_dup_char(PG_FUNCTION_ARGS)
{
text*arg0=PG_GETARG_IF_EXISTS(0,TEXT_P,NULL);
intn=0;
char*str=text_to_cstring(arg0);
n=strlen(str);
int32arg1=PG_GETARG_IF_EXISTS(1,INT32,0);
int32arg2=PG_GETARG_IF_EXISTS(2,INT32,n);
if(!(1<=arg1&&arg1<=n))
{
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("1<=arg1&&arg1<=n")));
}
if(!(1<=arg1&&arg1<=arg2&&arg2<=n))
{
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("1<=arg1&&arg1<=arg2&&arg2<=n")));
}
remove_dup(str,arg1,arg2);
PG_RETURN_TEXT_P(cstring_to_text(str));
}
void
remove_dup(char*str,intstart,intend)
{
inti=start-1,k=start-1;
for(i=start-1;i<=end-1;i++)
{
if(str[i+1]&&str[i+1]==str[i]&&i+1<=end-1)
{
k++;
}
else
{
str[i-k]=str[i];
}
}
str[i-k]='\0';
}
以上就是C语言去除相邻重复字符函数的实现方法，如有疑问请留言或者到本站社区交流讨论，感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！