Vb string to double vs mfc cstring to double

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5.00/5 (1 vote)

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Hi,

i had got issue regarding VB String to double conversion and C++ CString to double conversion.

i have a value in VB :

String -> 2.48365014976068

in VB they are using Val function while converting to double they are getting the same value in double as well i.e (2.48365014976068)

in C++:

String -> 2.48365014976068

in C++ while converting from CString to double the value in double is ( i.e 2.4836501497606802)

both vb and c++ giving different values ..please help me

What I have tried:

VB:
double d = Val(2.48365014976068)

C++:
double d = _tsof(2.48365014976068)

Posted 31-May-17 5:28am

Member 12677926

Updated 31-May-17 6:23am

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Richard MacCutchan · Answer 1 · 2017-05-31T06:23:00

Solution 1

No, the values are both the same. It is only the string representation that is different. See What Every Computer Scientist Should Know About Floating-Point Arithmetic[^].

Posted 31-May-17 6:23am

Richard MacCutchan

Comments

Maciej Los 31-May-17 14:14pm

5ed!

Member 12677926 31-May-17 23:22pm

string representation is fine i think .. could you please exaplain how it is wrong .as showing different values

Richard MacCutchan 1-Jun-17 4:28am

Nothing is wrong. Floating point numbers can be displayed to any precision, within the ranges described at Data Type Ranges[^]. If you do not understand how floating point numbers work in computers then you should avoid using them and stick to integer or decimal types.