C语言从txt文件查找字符串求助

txt文件内容如下:

A->B
hello everybody haha hehe
B->A
world is big
A->B
impossible is nothing
B->A
just do it
需求：
首先查找字符串hello，找到后提取其上一行字符串A->B，然后依次查找下一个A->B或者B->A（两个都可以），提取出其下一行第一个字符串，也就是world ,impossible ,just 然后把hello,world,impossible,just放到一个数组里。

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

struct st_result{
                char caStr[ 100 ];
                struct st_result *next;
        };

int fetch_string( char *cpPath, struct st_result **stpResult);
int clear_result( struct  st_result *stpResult);

int
main( int argc, char *argv[] )
{
        struct st_result *stpResult = NULL;
        int  iRet = 0;

        if( argc != 2 )
        {
                fprintf( stderr, "usage: %s file\n", argv[ 0 ] );
                return -1;
        }

        iRet = fetch_string( argv[ 1 ], &stpResult );
        if( iRet == 0 )
        {
                struct st_result *stpTmp = stpResult;

                while( stpTmp != NULL )
                {
                        printf( "str: %s\n", stpTmp->caStr );
                        stpTmp = stpTmp->next;
                }
        }

        clear_result( stpResult );

        return iRet;
}

int
fetch_string( char *cpPath, struct st_result **stpResult )
{
        FILE *fp = NULL;
        char caPreLine[ 512 ];
        char caCurLine[ 512];
        char caPreStd[ 128 ];
        char caEndStd[ 128 ];
        char caStrStd1[ 512 ];
        char caStrStd2[ 512 ];

        if( ( fp = fopen( cpPath, "r" ) ) == NULL )
        {
                fprintf( stderr, "fopen error\n" );
                return -1;
        }

        while(  fgets( caCurLine, 512, fp ) != NULL )
        {
                struct st_result *stpTmp = NULL;
                char   *cpTmp = NULL;

                if( caCurLine[ strlen( caCurLine ) - 1 ] == '\n' )
                        caCurLine[ strlen( caCurLine ) - 1 ] = '\0';

                if( strstr( caCurLine, "hello" ) == NULL )
                {   /* not find the 'hello' */
                        strcpy( caPreLine, caCurLine );
                        continue;
                }
                /* find the hello */
                if( ( stpTmp = malloc( sizeof( struct st_result ) ) ) == NULL )
                {
                        fprintf( stderr, "malloc error\n" );
                        return -1;
                }

                stpTmp->next = *stpResult;
                *stpResult = stpTmp;
                sscanf( caCurLine, "%s", stpTmp->caStr );

                sscanf( caPreLine, "%[^-]", caPreStd );
                if( ( cpTmp = strstr( caPreLine, "->" ) ) != NULL )
                {
                        strcpy( caEndStd, cpTmp + strlen( "->" ) );
                }
                strcpy( caStrStd1, caPreLine );
                sprintf( caStrStd2, "%s->%s", caEndStd, caPreStd );

                break;
        }

        memset( caPreLine, 0x0, sizeof( caPreLine ) );
        while( fgets( caCurLine, 512, fp ) != NULL )
        {
                struct st_result *stpTmp = NULL;

                if( caCurLine[ strlen( caCurLine ) - 1 ] == '\n' )
                        caCurLine[ strlen( caCurLine ) - 1 ] = '\0';

                /* if previous line is A->B or B->A */
                if( strstr( caPreLine, caStrStd1 ) != NULL || strstr( caPreLine, caStrStd2 ) != NULL )
                {
                        if( ( stpTmp = malloc( sizeof( struct st_result ) ) ) == NULL )
                        {
                                clear_result( *stpResult );
                                fprintf( stderr, "malloc error\n" );
                                return -1;
                        }

                        stpTmp->next = *stpResult;
                        *stpResult = stpTmp;

                        sscanf( caCurLine, "%s", stpTmp->caStr );
                        strcpy( caPreLine, caCurLine );
                }
                else
                        strcpy( caPreLine, caCurLine );
        }
        return 0;
}

int
clear_result( struct  st_result *stpResult)
{
        while( stpResult != NULL )
        {
                struct st_result *stpTmp = stpResult;

                stpResult = stpResult->next;
                free( stpTmp );
        }

        return 0;
}

读取这个txt文件，根据'\n'换行符判断是否换行取字符串，根据'\0'空格键判断第一个字符串的截取位置。逻辑很清晰，用C写不难。

为什么要首先查找hello呢？
直接查找A->B或者B->A不是同样的效果吗？
这样代码实现起来简单的多。