有如下程序,若文本文件mf1.dat中原有内容为ABC，则运行程序后文件mf1.dat中的内容为( )。#include#includevoid main(){FILE *fp1;fp1=fopen("mf1.txt","w");if (fp1 == NULL){ printf("cannot open the file.\n");exit(0);}fprintf(fp1,"abc");fclose(fp1);}