I’ve been going back and forth between C++ and C# alot in my current job. When switching between languages, certain elements bleed together leading to the same mistakes over and over. Some of mine:

C# to C++

• Putting array braces ([]) on the type instead of the variable name (eg, int[] whatever in C# vs int whatever[] in C++)
• Writing string literals with naked double quote (ala ") instead of the L prefix to denote Unicode
• Naming methods with PascalCase instead of the camelCase in our C++ convention
• Throwing exceptions with new, which particularly sucks since it won’t yield a compile error