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Lecture Introduction to computer and programming - Lecture No 26

The contents of this chapter include all of the following: Functions and the lambda calculus; haskell: Introduction, expressions, lists and list comprehensions, elementary types and values, control flow, defining functions, tuples. | CSC103: Introduction to Computer and Programming Lecture No 26 Previous lecture Pointer to a structure Dynamic memory allocation for structure Passing a structure to a function Today’s lecture outline Example program – structure C preprocessor directives Macro expansion File inclusion Conditional Compilation Example Program Create a structure to specify data on students given below: Roll number, Name, Department, Course, Year of joining Create a variable of that structure, input value from user and then display those values. Write a program Preprocessor directive Preprocessor directives are the special instruction to C compiler Preprocessor directive are resolved before compilation of program Each preprocessor directive begins with # and can be placed anywhere in the program Following preprocessor directives are used mostly Macro expansion File inclusion Conditional Compilation Macro expansion Preprocessor Macro definition Cont. && || Cont. A #define directive could be used to replace a condition Cont. A #define directive could be used to replace an entire C statement. Macros with Arguments Preprocessor Multi line marcos Go to program Macros versus Functions It seams that macro calls are ‘like’ function calls, they are not really the same things In a macro call the preprocessor replaces the macro template with its macro expansion In function call control is transferred to a function, function do processing and then control is returned back Macro call and expansion Cont. when is it best to use macros with arguments and when is it better to use a function Usually macros make the program run faster but increase the program size whereas functions make the program smaller and compact E.g. if we used macro 100 times, then macro expansion goes in source code 100 time before compilation process If a function is called 100 times, it will make same amount of space in the program Cont Conclusion: If macro is simple and small than it can be used to avoid function calls . | CSC103: Introduction to Computer and Programming Lecture No 26 Previous lecture Pointer to a structure Dynamic memory allocation for structure Passing a structure to a function Today’s lecture outline Example program – structure C preprocessor directives Macro expansion File inclusion Conditional Compilation Example Program Create a structure to specify data on students given below: Roll number, Name, Department, Course, Year of joining Create a variable of that structure, input value from user and then display those values. Write a program Preprocessor directive Preprocessor directives are the special instruction to C compiler Preprocessor directive are resolved before compilation of program Each preprocessor directive begins with # and can be placed anywhere in the program Following preprocessor directives are used mostly Macro expansion File inclusion Conditional Compilation Macro expansion Preprocessor Macro definition Cont. && || Cont. A #define directive could be used to replace