Share a multiple-choice question about define (including the replacement rules, program environment and preprocessing related knowledge of define during precompiling)

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Title

Catalog

Title

1. subject

2. Topic analysis

3. Question answer

4. Topic knowledge

4.1define Replacement rules

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Recommended reading order :

1. subject ->3. answer ->2. Topic analysis ->4. Topic knowledge

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1. subject

1、 Perform the following procedure , The correct output is （ ）

The following macro definitions are provided ：

#define N 3+1

#define Y(n) ((N+1)*n)

Then execute the statement z=2*(N+Y(5+1)) after ,z The value of is （）

A、60         B、190         C、248         D、 None of the above answers is correct  

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2. Topic analysis

This is a very typical #define The topic of the replacement rule of .

 

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3. Question answer

      right key ： A、60

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4. Topic knowledge

4.1define Replacement rules

Extend... In a program #define When defining symbols and macros , There are several steps involved .

1. When calling a macro , First, check the parameters , See if it contains any information from #define Defined symbols . If it is , They are replaced first .

2. The replacement text is then inserted into the program at the location of the original text . For macros , Parameter names are replaced by their values .

3. Last , Scan the result file again , See if it contains any information from #define Defined symbols . If it is , Just repeat Describe the process .

 

Please note that ：

Macro parameters are not entered after calculation, but directly replaced .

 

For more relevant knowledge, please see my blog ：

(1 Bar message ) Program environment and preprocessing ( Next ）：#define、#undef、 Command line compilation 、 Conditional compilation 、 File contains （ Super finishing , Recommended collection ！！！_vpurple__ The blog of -CSDN Blog
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