What is meant by a field
The consecutive nonwhite space characters that define a data item collectively define a field. It is possible to limit the number of such characters by specifying a maximum field width for that data item. To do so, an unsigned integer indicating the field width is placed within the control string, between the percent sign(%) and the conversion character. The dta item may contain fewer characters than the specified field width. However, the number of characters in the actual data item cannot exceed the specified field width. Any characters that extend beyond the specified field width will not be read. Such leftover characters may be incorrectly interpreted as the components of the next data item.
Example
# include
main()
{
int a,b,c;
.......
......
scanf("%3d %3d %3d",&a,&b,&c);
........
.......
}