这样H2CO3已经提到的，你可以使用线路长度为这样的：

 而（函数getline（安培;线，＆安培; line_size，F）！= -1）{    如果（strlen的（线）== 1）{
        的printf（H2CO3看准一个空行\\ n）;
    }    / *或*交替/
    如果（'\\ n'==行[0]）{
        的printf（埃德效治疗术也看准空行\\ n）;
    }    ..
}
 

while(getline (&line, &line_size, f) != -1){}  

I'm using this function to read line line. But i want to know when i'm reading a blank line. Can someone help?

so as H2CO3 already mentioned you can use the line length for this:

while (getline (&line, &line_size, f) != -1) {

    if (strlen(line) == 1) {
        printf("H2CO3 spotted a blank line\n");
    }

    /* or alternatively */
    if ('\n' == line[0]) {
        printf("Ed Heal also spotted the blank line\n");
    }

    ..
}