i have an input file named input.txt where all the data looks like
this:
(4,10) 20
(5,3) 13
(7,19) 6
..
..
..
the numbers are random. i need to use every number in each line
individually as an integer. i know how to use ifstream to get every
line into a string variable, but i dont know how to manipulate it to
get three different int variables out of that one string variable.
so my string is string line = "(4,10) 20";
what do i do?
can somebody help me please? 4 2570
dor wrote: i have an input file named input.txt where all the data looks like this: (4,10) 20 (5,3) 13 (7,19) 6 . . .
the numbers are random. i need to use every number in each line individually as an integer.
I doubt it. I guess you really should have a class that contains
exactly three
integers, and create one instance of that class per line. Let's call it
class X;
i know how to use ifstream to get every line into a string variable, but i dont know how to manipulate it to get three different int variables out of that one string variable. so my string is string line = "(4,10) 20";
What would you do if you'd have a std::istream& operator<<
(std::istream&, X) ?
HTH,
Michiel Salters
"dor" <ke*****@gmail. com> wrote in message
news:11******** **************@ i39g2000cwa.goo glegroups.com.. . i have an input file named input.txt where all the data looks like this: (4,10) 20 (5,3) 13 (7,19) 6 . . .
the numbers are random. i need to use every number in each line individually as an integer. i know how to use ifstream to get every line into a string variable, but i dont know how to manipulate it to get three different int variables out of that one string variable. so my string is string line = "(4,10) 20"; what do i do? can somebody help me please?
look at std::string's find_first_of and related functions.
I.E. this outputs "4":
std::string MyString = "(4,10) 20";
std::cout << MyString.substr (1, MyString.find_f irst_of(",") - 1);
then if you took the substr of the find_first_of + 1 until the first ) - 1
you would get the 10.
etc..
To convert them to numbers you have your choice of ways. My favorite way is
like this:
#include <sstream>
template<typena me T, typename F > T StrmConvert( F from )
{
std::stringstre am temp;
temp << from;
T to = T();
temp >> to;
return to;
}
Used like this:
RefreshRate = StrmConvert<int >( Refresh );
where Refresh is a std::string
this StrmConvert is quite useful and can convert int/float/std::string
etc... to/from each other.
This is not the only way, but is the way I would do it. If you have any
more question ask.
In article <11************ **********@i39g 2000cwa.googleg roups.com>,
"dor" <ke*****@gmail. com> wrote: i have an input file named input.txt where all the data looks like this: (4,10) 20 (5,3) 13 (7,19) 6 . . .
the numbers are random. i need to use every number in each line individually as an integer. i know how to use ifstream to get every line into a string variable, but i dont know how to manipulate it to get three different int variables out of that one string variable. so my string is string line = "(4,10) 20"; what do i do? can somebody help me please?
istream& read( istream& in, int& a, int& b, int& c ) {
int ta, tb, tc;
char ch;
if ( ! ( in >> ch && ch == '(' &&
in >> ta >> ch && ch == ',' &&
in >> tb >> ch && ch == ')' &&
in >> tc ) )
in.clear( ios_base::badbi t );
else {
a = ta;
b = tb;
c = tc;
}
return in;
}
--
Magic depends on tradition and belief. It does not welcome observation,
nor does it profit by experiment. On the other hand, science is based
on experience; it is open to correction by observation and experiment.
In article <2R************ **@fe04.lga>,
"Jim Langston" <ta*******@rock etmail.com> wrote: "dor" <ke*****@gmail. com> wrote in message news:11******** **************@ i39g2000cwa.goo glegroups.com.. .i have an input file named input.txt where all the data looks like this: (4,10) 20 (5,3) 13 (7,19) 6 . . .
the numbers are random. i need to use every number in each line individually as an integer. i know how to use ifstream to get every line into a string variable, but i dont know how to manipulate it to get three different int variables out of that one string variable. so my string is string line = "(4,10) 20"; what do i do? can somebody help me please?
look at std::string's find_first_of and related functions.
I.E. this outputs "4":
std::string MyString = "(4,10) 20"; std::cout << MyString.substr (1, MyString.find_f irst_of(",") - 1);
then if you took the substr of the find_first_of + 1 until the first ) - 1 you would get the 10.
etc..
To convert them to numbers you have your choice of ways. My favorite way is like this:
#include <sstream> template<typena me T, typename F > T StrmConvert( F from ) { std::stringstre am temp; temp << from; T to = T(); temp >> to; return to; }
Used like this: RefreshRate = StrmConvert<int >( Refresh ); where Refresh is a std::string
this StrmConvert is quite useful and can convert int/float/std::string etc... to/from each other.
This is not the only way, but is the way I would do it. If you have any more question ask.
That is certainly one way to do it. (I came up with about 5 different
ways before posting, including the above.) I didn't like the idea of
reading from the stream, then putting parts of the data back into a
stream just to read it out again.
That said, one method I cam up with was:
bool not_digit( char c ) {
return ! isdigit( c );
}
istream& read( istream& in, int& a, int& b, int& c ) {
string str;
getline( in, str );
replace_if( str.begin(), str.end(), ¬_digit, ' ' );
stringstream ss( str );
ss >> a >> b >> c;
return in;
}
But the above doesn't check the format of the input file.
and of course there is the C-ish way:
istream& read( istream& in, int& a, int& b, int& c ) {
string str;
getline( in, str );
if ( sscanf( str.c_str(), "(%d,%d) %d", &a, &b, &c ) != 3 )
in.clear( ios_base::badbi t );
return in;
}
But there's some duplication in the above I don't like.
--
Magic depends on tradition and belief. It does not welcome observation,
nor does it profit by experiment. On the other hand, science is based
on experience; it is open to correction by observation and experiment. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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