What type of errors are reported by the compiler?

Answer 1

That depends on the language, and in part on the compiler. A good compiler can find lots of different errors, for example:

A variable that is used before being declared.

• Type incompatibility.
• A variable is used that hasn't been assigned a value before. (This would mean that any garbage that happened to be at that position in memory would be used, instead of using a known value.)
• A variable is assigned a value, but that variable is never used. This would usually be only a warning - nothing bad would happen, but some lines in your program would be superfluous.
• Array out of bounds - for example, an array has 5 elements, numbered 0-4, and you are trying to access element #5, or element # minus 1.
• A mismatch between open and close parentheses, braces, if/endif, etc.
• A function or method has been declared to return a certain data type, but in the return statement you return a different data type - or no data at all.

  And many more. If you do some programming, you will soon see the compiler catching all kinds of mistakes.

Answer 2

The compiler can detect all kinds of syntactical errors like:

• referring to a method that doesnt exist
• assigning objects of one type to another without explicit casting
• trying to access private methods of another class
• etc.

The purpose of the compiler is to detect these kind of programming problems in the code.

Answer 3

Linker errors. When you got those errors you forgot to include a library or a header file, which contains functions used in your program.