[C supplement] [string] display the schedule of a month by date

1、 Program description

   requirement ： The user enters a series of schedules in a fixed format （ Input 0 Stop when ）, The program sorts them by date , And display line by line .

   Input format ： “ date event ”. for example “24 Mom’s birthday”

2、 Ideas

2.1 String storage form

• Store the date and event in the read string separately (scanf Read date ,getchar Read the event strings one by one ), For later comparison and sorting .
• Sort (strcpy function ) After the end , The two merge (strcat function ) Storage , Stored in a two-dimensional character array ;
• Output the sorted and merged character array line by line .

2.2 Method of sorting storage

1. Date of withdrawal , Separate storage , Compare it with previous dates (strcmp function );
     The previous date has been stored before the schedule string 2 position , from strcmp function Comparison mechanism , There is no need to extract separately
2. Find a bigger line , Move the remaining lines down one line , Vacate the position of the line ;
     By the array storage mechanism , Moving down is actually moving back
3. Store the complete content corresponding to the date in the empty line .

3、 Code

/************************************ *  Show the schedule list of a month  * * **********************************/

#include<stdio.h>
#include<string.h>

#define MAX_REMIND 50 // Maximum number of events 
#define MSG_LEN 60 // The upper limit of the length of each event description 

int read_line(char str[], int n);     // Read the event content and store 

int main(void)
{
    
	char reminders[MAX_REMIND][MSG_LEN+3];  //+3 Is to reserve the position of date and empty character of string 
	char day_str[3], msg_str[MSG_LEN+1];    // Temporarily store dates and events 
	int day, i, j;
	int num_remind = 0;                     // Record the number of schedules read 
	
	// Set up a dead cycle , Ensure that users can input continuously 
	for(;;){
    
		
		// Limit the number of reads 
		if(num_remind == MAX_REMIND){
    
			printf("————————————  The schedule has reached the upper limit  ————————————\n");
			break;
		}
		
		printf("Enter day and reminder: ");
		scanf("%2d", &day);                 // Read the first two digits 
		if(day == 0) break;                 // Read terminated 
		sprintf(day_str, "%2d", day);       // Convert date to string storage , Align right in two spaces 
		read_line(msg_str, MSG_LEN);        // Read events and store 
		
		
		/******** Sort by date ********/
		
 		// Line by line comparison , Find the right place (i)
		for(i=0; i<num_remind; i++){
    
			if( strcmp(day_str, reminders[i]) < 0 ) break;
		}
		// Leave the line where the position is located ( The string below it moves down one line )
		for(j=num_remind; j>i; j--){
    
			strcpy( reminders[j], reminders[j-1] );
		}
		
		// Merge and store dates and events 
		strcpy( reminders[i], day_str );
		strcat( reminders[i], msg_str );
		
		num_remind++;
	}
	
	// Show the sorted schedule line by line 
	printf("\n\nDay Reminder: \n");
	for(i=0; i<num_remind; i++){
    
		printf(" %s\n", reminders[i]);
	
	
	return 0;
}

int read_line(char str[], int n)
{
    
	int i=0, ch;
	while( (ch=getchar()) != '\n' )      // Spaces are not skipped ( And scanf Different )
		if(i<n) str[i++] = ch;
	
	str[i] = '\0';                       // Add empty characters at the end of the character array , Become a string 
	
	return i;                            // Returns the length of the character array 
}

4、 Examples of run results