What are the bad habits of C programmers starting to write C++? [closed]

Answer 1

• using char* instead of std::string
• using arrays instead of std::vector (or other containers)
• not using other STL algorithms or libraries like boost where appropriate
• abusing the preprocessor where constants, typedefs or templates would have been better
• writing SESE-style (single-entry single exit) code

Answer 2

Declaring all the variables at the top of a function instead of as close as possible to where they are used.

Answer 3

Not using the STL, especially std::string,

and/or

using std::strings and reverting to old c string functions in tight corners.

Answer 4

using pointers instead of references

Answer 5

Well, bad program design transcends languages ( casts, ignoring warnings, unnecessary precompiler magic, unnecessary bit-twiddling, not using the char classification macros ) , and The C language itself doesn't create too many "bad habits" ( Ok, Macros, esp from the stone ages ), and many of the idioms translate directly. But a few that could be considered:

Using a feature just because it's in C++ and so therefore it must be the right way to do something. Some programs just don't need Inheritance, MI, exceptions, RTTI, templates ( great as they are ... the debugging load is steep ), or Virtual class stuff.

Sticking with some code snippet from C, without thinking if C++ has a better way. ( There's a reason you now have class, private, public, const (expanded beyond C89) , static class funcs, references.

Not being familiar with the C++ i/o lib ( its BIG, and you do need to know it) , and mixing C++ i/o and C i/o.

Answer 6

Declaring all the variables at the start of the function itself even if the variable will be used only after 100 lines or so.

Happens especially for local variables declared inside a function.