File reading problem

Basically, why is

in.ignore('v');
in.ignore(' ');
sscanf(c,"%f %f %f",&f1,&f2,&f3);

not the same as

sscanf(c,"v %f %f %f",&f1,&f2,&f3);

when reading the line (from file)

v 0.467854 0.394649 -1.000000

The 1st code does not work, while the 2nd does work. Why does the 1st code not work?


According the documentation, ifstream::ignore will remove characters until it finds the argument('v', for example), and also remove the argument('v'), so the two codes should work the same, right?

Documentation:

istream&  ignore ( streamsize n = 1, int delim = EOF );

Extracts characters from the input sequence and discards them.
 
The extraction ends when n characters have been extracted and discarded or when the character delim is found, whichever comes first. In the latter case, the delim character itself is also extracted.