| Compile-time expansion | Macro functions are expanded by the preprocessor at the compile time. | Inline functions are expanded by the compiler. |
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| Argument Evaluation | Expressions PASSED to the Macro functions might get evaluated more than once. | Expressions passed to Inline functions get evaluated once. |
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| Parameter Checking | Macro functions do not follow STRICT parameter DATA TYPE checking. | Inline functions follow strict data type checking of the parameters. |
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| Ease of debugging | Macro functions are hard to debug because it is replaced by the pre-processor as a textual representation which is not visible in the source code. | Easier to debug inline functions which is why it is recommended to be used over macro functions. |
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| Example | #define SQUARENUM(A) A * A -> The macro functions are expanded at compile time. Hence, if we pass, the output will be evaluated to 3+2*3+2 which gets evaluated to 11. This might not be as per our expectations. | inline squareNum(int A){return A * A;} -> If we have printf(squareNum(3+2));, the arguments to the function are evaluated FIRST to 5 and passed to the function, which returns a square of 5 = 25. |
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