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string to double

Posted on 2003-12-11
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Last Modified: 2006-11-17
i get a string from a line I'm parsing.

string notdegree= buf[2];    returns a number but its a string

string degree=  notdegree.substr(0,5); returns the part of the number i want still a string

         indegree = degree/60  -- i need to be able to do this  -- how do I change something from a string to a number

the following is the error i get

C:\Program Files\Microsoft Visual Studio\MyProjects\parse\parse.cpp(98) : error C2676: binary '/' : 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >' does not define this operator or a conversion to a type acc
eptable to the predefined operator
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Question by:tpiazza
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LVL 19

Accepted Solution

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Dexstar earned 50 total points
ID: 9922388
@tpiazza:

> indegree = degree/60  

Try this:

     indegree = atof(degree.c_str())/60.0f;

Hope That Helps,
Dex*
0
 

Author Comment

by:tpiazza
ID: 9922527
tried that it errors out

C:\Program Files\Microsoft Visual Studio\MyProjects\parse\parse.cpp(100) : error C2664: 'atof' : cannot convert parameter 1 from 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >' to 'const char *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
Error executing cl.exe.
0
 

Author Comment

by:tpiazza
ID: 9922539
take that back -- it works now

indegree = atof(degree.c_str())/60.0;

.c_str() -- I dint have that -- what does it do?

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LVL 9

Expert Comment

by:tinchos
ID: 9922578
c_str method

Returns a pointer to a null-terminated array of characters representing the string's contents.

Tincho
0
 
LVL 19

Expert Comment

by:Dexstar
ID: 9922621
It returns a const char* to the data in the string...  :)

Dex*
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