以下程序运行后,文件test.txt的内容是( )。 #include <stdio.h> main() { FILE *fp; char str[][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); }