C语言实现字符串切片

    因要用C语言实现读取配置文件，配置文件中字符串以逗号分隔，所以要根据索引获取到相应位置的字符串，也要能根据字符串获取在一串字符中的索引，代码记录如下：

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

int findSubstringIndexSplitByComma(const char *pSrc, const char *pDst);
int getSubstringByIndexSplitByComma(const char *pSrcString,const int index,char *pSubString,const int pSubStringSize);

void main(void)
{
char *p_src_string = "S1,S2,S3,S4,S5,S6,S7";
char *p_need_find_string = "S6";
char sub_string[10] = {};
int index = 0;

index = findSubstringIndexSplitByComma(p_src_string,p_need_find_string);
if(-1 != index)
{
printf("The index of SubString[%s] in SrcString[%s] is [%d]\n",p_need_find_string,p_src_string,index);
}

if(-1 != getSubstringByIndexSplitByComma(p_src_string,index,sub_string,sizeof(sub_string)))
{
printf("Get sub string from SrcString[%s] by index[%d]:SubString--[%s]\n",p_src_string,index,sub_string);
}
else
{
printf("Can not find SubString in [%s] by index[%d]\n",p_src_string,index);
}

}
//if can not find substring in srcString,return -1
//if can find,return the num of comma before the substring
//for example:
//srcstring S1,S2,S3 subString:S2,return 1
//srcstring S1,S2,S3 subString:S4,return -1
int findSubstringIndexSplitByComma(const char *pSrc, const char *pDst)
{
int i = 0;
int j = 0;
int comma_cnt = 0;

for (i=0; pSrc[i]!='\0'; i++)
{
if(',' == pSrc[i])
{
comma_cnt++;
}

if(pSrc[i]!=pDst[0])
continue;

j = 0;
while(pDst[j]!='\0' && pSrc[i+j]!='\0')
{
j++;
if(pDst[j]!=pSrc[i+j])
{
break;
}
}
if(pDst[j]=='\0')
return comma_cnt;
}
return -1;
}

//if can not find substring by index in srcstring,return -1
//if can find,return 0,and cpy this subString to pSubString,so you need ensure the pSubString has enough space to save the substring
//srcString ",,,",if index = 1,substring is empty,if the substring space is not enough,cut short the subString in srcString
//pay attention to the index = 0,if the index is 0,find_index = 0
int getSubstringByIndexSplitByComma(const char *pSrcString,const int index,char *pSubString,const int pSubStringSize)
{
int comma_cnt = 0;
int i = 0;
int j = 0;
int find_index = 0;

//get srcString comma cnt,if equal the index,start copy to the pSubString
for(i = 0;pSrcString[i] != '\0';i++)
{
if(comma_cnt == index)
{
break;
}
if(',' == pSrcString[i])
{
comma_cnt++;
}
}
//can not find the index of comma_cnt,just return
if('\0' == pSrcString[i])
{
return -1;
}
//find
find_index = i;
for(j = 0;('\0' != pSrcString[j + find_index]);j++)
{
if(j < pSubStringSize)
{
if(',' == pSrcString[j + find_index])
{
break;
}
else
{
pSubString[j] = pSrcString[j + find_index];
}
}
else
{
printf("The subString space is not enough\n");
break;
}
}
pSubString[j] = '\0';

return 0;
}


    运行结果如下：
[root@localhost test]# gcc test.c -o test
[root@localhost test]# ./test
The index of SubString[S6] in SrcString[S1,S2,S3,S4,S5,S6,S7] is [5]
Get sub string from SrcString[S1,S2,S3,S4,S5,S6,S7] by index[5]:SubString--[S6]


    如果大家有更好的实现方法，请多多指教。