strsep 分割字符串后，如何控制只输出部分子串

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <regex.h>


int main(int argc,const char *argv[])
{
        FILE *fp;
        size_t len = 0;
        char *str = NULL;
        ssize_t read;
        
        // reg compile
        regex_t reg;
        const char *pat = "^##";
        int cflags = REG_EXTENDED | REG_NEWLINE;
        int ret = regcomp(&reg,pat,cflags);
        char err_info[256];

        // search
        const size_t nmatch = 1;
        regmatch_t pmatch[nmatch];

        if(argc != 2)
        {
                fprintf(stderr,"usage: %s <src>\n",argv[0]);
                exit(1);
        }

        if((fp=fopen(argv[1],"r")) == NULL)
        {
                perror("fopen()");
                exit(1);
        }
        
        if(ret!=0)
        {
                regerror(ret,&reg,err_info,256);
                fprintf(stderr,"%s\n",err_info);
                regfree(&reg);
                exit(1);
        }
        char *line = NULL;
        while((read = getline(&str,&len,fp)) != -1)
        {
                str[read-1]='\0';
                int reg_res=regexec(&reg,str,nmatch,pmatch,0);
                if(reg_res == 0)
                        continue;
               
                while((line = strsep(&str,"\t")) != NULL)
                {
                        fprintf(stdout,"%s-->",line);    ## 就是这里不知道该怎么处理了
                }
                printf("\n");

        }
        regfree(&reg);
        fclose(fp);

        exit(0);
}