Talk:Data Analysis using the SAS Language/Data Step

dear all:

    I am confused when i study this chapter.the main questions are as follows;
    1) what's the difference between format and informat;
       i have write a program to read a survey data and my program are write as follows:
           data survey;
           infile "F:/data/survey.txt";
           input name$ 15. height 3.2  birthday MMDDYY10.;
           run;
        but i have encountered some troubles. the height couldn't be read by SAS.so,I change my program use informat option.
           data survey;
           infile "F:/data/survey.txt";
           informat name$ 15. height 3.2  birthday MMDDYY10.;
           input name height birthday MMDDYY;
           run;
        this can be read by sas normally. why?
    2) is "input var1 10.0 +1 var2 10.0" identical to "input var1 10.0 @11 var2 10.",as the note told us"+1 means to skip one character".