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Second assignment

2020-11-08 10:05:54 He is a famous Chinese character

0. Exhibition PTA Total score


1. Summary of this chapter

1.1 Summary of this chapter and 1.2 Summary of programming skills

  1. Variable name : Little hump nomenclature example :aB
    Function name : The name of the great hump example :Ab
  2. c The identifier in a language consists of letters Numbers Underline composition , The first character must be Letters or underscores .
  3. int( integer ) char( Character ) float( Single precision floating point ) double( Double precision floating point )typedef( Custom type )
  4. / written words / Comment lines
    //: Note a single line
  5. (1) Two integers are divided , The result of the operation is an integer .
    example :10/4=2 1/3=0
    (2) The remainder
    example :5%6=5 9%4=1 100%4=0( It means that it can be divisible )
    (3) To convert to floating point , You need to convert one of the numbers into floating-point numbers
    example :10.0/4 10.0/4.0
  6. (1) Format input function scanf()
    int Type data %d float Type data %f doouble Type data %lf
    example :scanf("%lf",&x); ( Pay attention to the type of data entered , Control the character with the corresponding format ,& Don't miss it. )
    (2) Format output function printf()
    int Type data %d fioat and double Type data are available %f,double The model can also be used %lf
    %nf Indicates that the output data is reserved after the decimal point n position
    %f The decimal point is reserved by default 6 position
    example :printf("%d %f %.3f",a,b,c);
  7. Generate random number
    example :
    #include <stdio.h>
    #include <stdlib.h>
    #include <time.h>
    int main()
    {
     int number;             // A variable that defines a random number 
     srand(time(0));         // Produce seeds 
     number = rand() % 100;  // The range of generating random numbers is 0-100
     printf("%d", number);   // Output random number 
     return 0;
    }
    
    If the range of random numbers generated is 10-100, The code for the scope is changed to :number=10+rand()%90;
  8. Relational operator
    == equal != Unequal
  9. Mathematical functions
    Call I / O function , To add #include <stdio.h> Call mathematical function , To add #include <math.h>
    Square root function : sqrt(x) example : sqrt(4.0)=2.0
    Absolute value function : fabs(x) example : fabs(-5.0)=5.0
    power function : pow(x,n) example : pow(4,2)=16
    Exponential function exp(x) example : exp(2.3) The value of is e Of 2.3 Power
  10. Control the number of outputs
    %md If the number of digits is less than m, Will automatically fill in the space from the left
    %-md If the number of digits is less than m, Will automatically fill in the space from the right
    %m.nf m Including the sign place and the decimal point ,n Express reservation n Decimal place
    example :
    #include <stdio.h>
    int main()
    {
       int number1,number2;
       double number3;
       scanf("%d %d %lf", &number1,&number2,&number3);
       printf("%5d%-5d%5.3f", number1,number2,number3);
       return 0;
    }
    
    When the input 30 50 5.5 when , The output is : Three spaces +3050 Three spaces +5.500
  11. Make the tail without spaces
    example :
    #include <stdio.h>
    int main()
    {
    int n = 3;
    int i;
    int flag = 1;
    int number;
    int a;
    for (i = 1; i <= 3; i++)
    {
    	scanf_s("%d", &a);
            number = a;
            if (flag == 1)                    // Find the first number , And change the output mode of the following numbers 
    {
    	flag = 0;
    	printf("%d", number);
    }
            else
    {
    	printf("a%d", number);
    }
    }
        return 0;
    }
    
    When the input 30 and 40 and 50 when , The output is 30a40a50, Can realize tail without space
  12. Character data
    The data of character type variable is used char To define , And add ''
    Commonly used decimal character type constant ASCII code :'a':97,'A':65,'0':48
    Character input and output functions :
    (1)getchar(): Only one character can be read in ,() There are no parameters in it
    (2)putchar(): Output a character , Format :putchar( Output parameters )
    example :
    #include <stdio.h>
    int main()
    {
    char ch;
    ch = 97;
    printf("%c %d", ch, ch);
        return 0;
    }
    
    The output is :ch 97
  13. Logical operations
    !: Not ,&&: And ,||: or
    && and || Has a lower priority than the relational operator
  14. Flexible use switch Statement break
    example : Show part of the code
    case n: case m: case f: ......case z:
     expression ;
    break;
    
    above case Common expressions
  15. Pseudo code descriptors
    example :
    (1)while Conditions
    expression
    end while
    (2) if Conditions
    expression
    end if
  16. n-- And --n A kind of distinction
    example :
    #include <stdio.h>
    int main()
    {
        int n;
        n = 8;
        printf("%d ", n--);
    }
    
    The output is 8
    #include <stdio.h>
    int main()
    {
        int n;
        n = 8;
        printf("%d ", --n);
    }
    
    The output is 7
  17. Take a number from a certain bit
    example :
    number It means a number ,n A number in one of its bits
    bits :n=number%10
    ten :n=number/10%10
    Hundred bit :n=number/100%10
    And so on
  18. Input 3 The number of outputs is maximum or minimum or middle or arranged in order of size
    Example :

    The code you started with :
    #include <stdio.h>
    
    int main()
    {
        int a,b,c;
        scanf("%d %d %d",&a,&b,&c);
        if(a>b)
        {
            if(b>c)
            {
                printf("x=%d,y=%d,z=%d",c,b,a);
            }
            else if(c>a)
            {
                printf("x=%d,y=%d,z=%d",b,a,c);
            }else
            {
                printf("x=%d,y=%d,z=%d",b,c,a);
            }
        }else
        {
            if(c>b)
            {
                printf("x=%d,y=%d,z=%d",a,b,c);
            }
            else if(a>c)
            {
                printf("x=%d,y=%d,z=%d",c,a,b);
            }else
            {
                printf("x=%d,y=%d,z=%d",a,c,b);
            }
        }
        return 0;
    }
    
    What happened : A lot of code , And the idea is complicated , It's not good for getting things done quickly .
    Learn to refer to the code replaced by intermediate quantity :
    #include <stdio.h>
    int main()
    {
        int number1,number2,number3, temp;
        scanf("%d %d %d", &number1, &number2, &number3);
        if (number1 > number2)
        {
    	    temp = number1; 
    	    number1 = number2;
    	    number2 = temp;
        }
        if (number1 > number3)
        {
    	    temp = number1;
    	    number1 = number3;
    	    number3 = temp;
        }
        if (number2 > number3)
        {
    	    temp = number2;
    	    number2 = number3;
    	    number3 = temp;
        }
        printf("x=%d,y=%d,z=%d", number1, number2, number3);
        return 0;
    }
    
    Easy to operate , And the idea is clear .
  19. Calculation 1-1/3+1/5-... A kind of question type ( introduce flag)
    Example :
    #include <stdio.h>
    
    int main()
    {
        int i;
        int n;
        int flag;
        double sum;
        scanf("%d", &n);
        flag = 1;
        sum = 0;
        for (i = 1; i <= n; i++)
        {
    	    sum = sum + flag*i * 1.0 / (2 * i - 1);
    	    flag = -flag;
        }
        printf("%.3f", sum);
        return 0;
    }
    
  20. Count the number of digits of an integer
    example :
    #include <stdio.h>
    
    int main()
    {
        int count, number;
        count = 0;
        scanf_s("%d",&number);
        while (number != 0)
        {
    	    count++;
    	    number = number / 10;
        }
        printf("%d", count);
        return 0;
    }
    

1.3 Learning experience of this chapter

Through these two weeks of study and review c Language related content , Because during the summer vacation, I have a little understanding of the previous content , So I can keep up with the class content , There is no problem with the structure and content of those statements , But some of the sentences are not very well understood , The basic reason is that there is no clear understanding of the basic content of the sentence , I don't know enough about the details , Including the preview of the textbook is not complete . After that, the class progress is a little fast ⊙ω⊙, Just after the preview, we should preview the next section immediately , A little too late to consolidate their own foundation , In the last two weeks, we have written the branch structure of the topic, and have written the experimental problem set published in class , And preview some topics in the courseware .

2.PTA Experiment assignment

2.1 The day before yesterday

2.1.1 Data processing

Variable :

  • year( year )( integer ): The day before yesterday, it might be another year
  • month( month )( integer ): The day before yesterday may involve a month change
  • day( Days )( integer ): It must involve the change of days
  • Febary( The number of days in February ): There are different February days between leap year and non leap year
  • mark( month /1)( integer ): Need to use switch sentence

2.1.2 Code screenshot

A little longer , Separate cut graphs



2.1.3 PTA Submit list and description


Q1: Looking for a long time exactly where programming errors or missing some letters and symbols
A1: The results are moving , Turned out to be case There's no number after it , Add the expression directly .....

Height difference of the best couple

2.2.1 Data processing

Variable :

  • sex( Gender )( Character ): Determine gender
  • n( The number of )( plastic ): Judge how many people
  • i( plastic ): Loop statements use
  • height( height )( integer ): Subject requirements
  • number( Suitable for height )( integer ): The optimum height after conversion

2.2.2 Code screenshot

2.2.3 PTA Submit list and description


The teacher has explained the input related question in class and typed the code , When I write by myself, I first write in vs Debug and correct, so the commit is correct

Step by step debugging ( Tortoise and the hare )

2.3.1 One step debug screenshot

2.3.2 Code screenshot


2.3.3 PTA Submit list and description


Q1: Only partially correct when submitted , Several parts of the judgment are missing
A1: Forget to judge whether the rabbit runs faster than the tortoise , Split the time directly every ten minutes , This leads to a partial lack of judgment .

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