C language 2: find the maximum value of three numbers, find the middle value of three numbers, and write program steps

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1. Example 1

Enter three numbers , Find the largest number

1.1 Ternary operator

#include<stdio.h>
int main()
{
    
	int a = 0, b = 0,c = 0;
	int max = 0;
	printf("input data:");
	scanf_s("%d %d %d", &a, &b, &c);
	max = a > b ? a : b;
	max = max > c ? max : c;
	
	printf("max %d \n", max);
	return 0;
}

1.2 if Nesting of statements

#include<stdio.h>
int main()
{
    
	int a = 0, b = 0,c = 0;
	int max = 0;
	printf("input data:");
	scanf_s("%d %d %d", &a, &b, &c);
	if (a > b && a > c)
	{
    
		max = a;
	}
	else if (b > a && b > c)
	{
    
		max = b;
	}
	else
	{
    
		max = c;
	}
	printf("max %d \n", max);
	return 0;
}

1.3 Code reuse is the highest （ Pass value assignment ）

#include<stdio.h>
int Max_Int(int a, int b)
{
    
	int c = a > b ? a : b;
	return c;
}
int main()
{
    
	int a = 0, b = 0, c = 0;// initialization 
	int max = 0;
	printf("input data:");
	scanf_s("%d %d %d", &a, &b, &c);
	max = Max_Int(a, Max_Int(b, c));// Value transfer call , Arguments are assigned to parameters 
	printf("max %d \n", max);
	return 0;
}
// Code reuse is the highest , That is, the best execution method 

2. Example 2

Enter three numbers , Find the output intermediate value .

Algorithm implementation ： Bubble sort , Enter three values , First sort the three values , Output intermediate value , This is the number you want .

2.1 The wrong sample

Code redundancy , Did not pay attention to the code writing specification

#include<stdio.h>
int main()
{
    
	int a = 0, b = 0, c = 0;
	int mid = 0;
	printf("input data:");
	scanf_s("%d %d %d", &a, &b, &c);
	if (a > b)
	{
    
		int tmp = a;
		a = b;
		b = tmp;
	}
	if (b > c)
	{
    
		int tmp = b;
		b = c;
		c = tmp;
	}
	if (a > b)
	{
    
		int tmp = a;
		a = b;
		b = tmp;
	}
	mid = b;
	printf("mid=%d \n", mid);

	return 0;
}

2.2 Method 1

The main function is separated from other functions , Code algorithm implementation is clearly visible , Code writing is standard, clear and good

#include<stdio.h>
int Mid_Int(int a, int b, int c)
{
    
	if (a > b)
	{
    
		int tmp = a;
		a = b;
		b = tmp;
	}
	if (b > c)
	{
    
		int tmp = b;
		b = c;
		c = tmp;
	}
	if (a > b)
	{
    
		int tmp = a;
		a = b;
		b = tmp;
	}
	return b;
}

int main()
{
    
	int a = 0, b = 0, c = 0;
	int mid = 0;
	printf("input data:");
	scanf_s("%d %d %d", &a, &b, &c);
	mid = Mid_Int(a, b, c);
	printf("mid=%d \n", mid);
	return 0;
}

2.3 Method 2

A formal parameter is defined as a pointer type , Delivery address ( Exchange function ）

#include<stdio.h>
void Swap_Int(int a, int b)
{
    
	int tmp = a;
	a = b;
	b = tmp;
}
int main()
{
    
	int x = 10, y = 20;
	Swap_Int(x, y);

	printf("x=%d,y=%d \n", x, y);
	return 0;
}

3. The steps and process of programming （ Suitable for beginners ）

（1） demand ： Put forward your own needs for code , Ask questions
（2） analysis ： Analyze the problems and requirements raised
（3） Design ： That is to design the algorithm of the code
（4） The implementation of ： Implementation of program code , That is, the implementation of coding
（5） test ： Test the code modules that you write your own code

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