what is a compiler ?

compiler is a software program which converts user written high level language program (also known as source program) into machine language. Computer can understand only machine language so before executing any program we need to convert it into machine language. When we compile any program it is converted into machine language which creates an object file. If a program has errors, compiler can not create an object file. When compilation errors exists it displays to the user by some error messages. Just suppose in Language C++ you forgot to put a ; semcolon at the end of the statement. Compiler raise an error "Statement missing". Compiler can show punctuation errors, syntax errors but can not show logical errors. Just suppose you have written a program to calculate simple interest and your formula of simple interest is wrong then the compiler can not show errors and the program will be executed successfully. There are seperate compilers available for each language. If you want to compile a program which is written in Pascal you nee a pascal compiler.