以下程序运行后，文件test.txt的内容是()。#include<stdio.h>void main(){ FILE*fp;charstr[][10]={"first","second"};fp = fopen("test.txt","w");if(fp!=NULL)fprintf(fp,"%s",str[0]);fclose(fp);fp = fopen("test.txt","w");if(fp!=NULL)fprintf(fp,"%s",str[1]);fclose(fp);}