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Branch if statement

2022-04-21 11:47:00 【wx6235761444879】

What is a sentence ？

 
       int 
       
       a 
       
       = 
       
       0;
       
       // A piece of code separated by English semicolons is a statement 
       
;
       
       // Empty statement 
       
       1
       
       +
       
       2;
      
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that if What is the structure of the statement ？

 
       1.
       
       if(
       
        expression )
       
        sentence ;
       
       2.
       
       if(
       
        expression )
       
        sentence ;
       
       else
       
        sentence ;
       
       3.
       
       if(
       
        expression 1)
       
        sentence ;
       
       else 
       
       if(
       
        expression 2)
       
        sentence ;
       
       else
       
        sentence ;  
      
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Look at the infrastructure , Let's write a piece of code ！

 
       #include <stdio.h>
       
       int 
       
       main()
       
{
       
       if(
       
       age
       
       <
       
       18)
       
      {
       
       printf(
       
       " A minor \n");
       
      }
       
       else 
       
       if(
       
       age 
       
       >= 
       
       18 
       
       && 
       
       age 
       
       <= 
       
       30)
       
       //&& Show and 
       
       printf(
       
       " adult \n");
       
       else 
       
       if(
       
       age 
       
       >
       
       30 
       
       && 
       
       age 
       
       <=
       
       60)
       
       printf(
       
       " middle-aged \n");
       
       else
       
       printf(
       
       " The elderly \n");
       
       return 
       
       0;
       
}
      
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The above code is in the form of structure three , So it's also possible to use structure 2 to write here

 
       #include <stdio.h>
       
       int 
       
       main()
       
{
       
       if(
       
       age
       
       <
       
       18)
       
      {
       
       printf(
       
       " A minor \n");
       
      }
       
       else 
       
      {
       
       if(
       
       age 
       
       >= 
       
       18 
       
       && 
       
       age 
       
       <= 
       
       30)
       
       //&& Show and 
       
       printf(
       
       " adult \n");
       
       else 
       
       if(
       
       age 
       
       >
       
       30 
       
       && 
       
       age 
       
       <=
       
       60)
       
       printf(
       
       " middle-aged \n");
       
       else
       
       printf(
       
       " The elderly \n");
       
      }
       
       return 
       
       0;
       
}
      
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Here's the point ,else How does this keyword work ？ Now let's talk about hanging else To understand the else Operation of

 
       #include <stdio.h>
       
       int 
       
       main()
       
{
       
       int 
       
       a 
       
       = 
       
       0;
       
       int 
       
       b 
       
       = 
       
       2;
       
       if(
       
       a 
       
       == 
       
       1)
       
       //== Said judgment 
       
      {
       
       if(
       
       b 
       
       == 
       
       2)
       
            {     
       
       printf(
       
       "hehe\n");
       
            }
       
      }
       
       else
       
       printf(
       
       "haha\n");
       
       return 
       
       0;
       
}
      
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Guess what the code output is ?

The output is nothing

Then why is this ？

The reason is simple , Don't think so complicated . The reason is that else And recent if matching

Come on , Let's see how the code works

Branch if sentence _#include

We Understand the hanging else , So how to modify this code ？

 
       int 
       
       main()
       
{
       
       int 
       
       a 
       
       = 
       
       0;
       
       int 
       
       b 
       
       = 
       
       2;
       
       if(
       
       a 
       
       == 
       
       1)
       
       {
       
       if(
       
       b 
       
       == 
       
       2)
       
       printf(
       
       "hehe\n");
       
       else
       
       printf(
       
       "haha\n");
       
       }
       
       return 
       
       0;
       
}
       
       // Of course, the result is nothing   When we get here, we understand that hanging in the air else
      
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summary ：

In the air else It's with the latest if Match

Here are some questions

 
       #incude <stdio.h>
       
       int 
       
       main()
       
{
       
       int 
       
       sum 
       
       = 
       
       4;
       
       if(
       
       sum 
       
       = 
       
       5)
       
       printf(
       
       "hehe\n");
       
       return 
       
       0;
       
}
      
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Let's think about the result first

The result is hehe

Do you really know this code ？（ As a beginner , I was wrong at a glance ）

Let me talk about how this code works

Branch if sentence _#include_02

Be careful ： Symbol = Indicates assignment , It's not judgment

Now let's look at another topic

Print out 1-100 All the odd numbers of

 
       #include <stdio.h>
       
       int 
       
       main()
       
{
       
       int 
       
       i 
       
       = 
       
       1;
       
       while(
       
       i
       
       <=
       
       100)
       
       //while  Represents a cycle 
       
      {
       
       if(
       
       i
       
       %
       
       2 
       
       == 
       
       1)
       
       //% Representation module 
       
           {
       
       printf(
       
       "%d ",
       
       i);
       
           }
       
       i
       
       ++;
       
      }
       
       return 
       
       0;
       
}
      
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here while Represents a cycle

This code is not hard , Simple . Come on , go

Branch if sentence _ assignment _03

You can also write like this

 
       #include <stdio.h>
       
       int 
       
       main()
       
{
       
       int 
       
       i 
       
       = 
       
       1;
       
       while(
       
       i
       
       <=
       
       100)
       
     {
       
       printf(
       
       "%d ",
       
       i);
       
       i
       
       +=
       
       2;
       
       //i+=2  Namely i=i+2;
       
     }
       
       return 
       
       0;
       
}
      
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This is it. if Branch , Simple understanding , Deep absorption

The point is to hang in the air else And some key symbols

Thank you for watching. ！

版权声明
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https://yzsam.com/2022/04/202204211109376722.html

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