The first day of C language daily question

#define _CRT_SECURE_NO_WARNINGS 1
#define N 5
#include<stdio.h>
int main()
{
	int i, j, k;     // Define three variables （ In fact, it won't take so much , Two will do ）
	for (i = 0; i < N; i++)     //N by 5, Just print five lines 
	{
		for (j = 0; j < N-i; j++)    // j<N-i  Is to print spaces on each line   first line 5 A space   The second line has four   The third line three   The fourth line has four   The fifth line is a space 
		printf(" "); 
		for (j = 0; j <= i; j++)     
			printf("%c", (char)('A' + j));   //  After typing the space in each line , No newline , Then type characters , The cast is used here ,'A'+1='B', Notice that here are the characters B
		for (k = i; k; k--)
			printf("%c", (char)('A' + k-1));  // The flashback character is printed here , The reason for subtracting one here , To avoid printing something like :ABBA, This is the case 
		printf("\n"); // Wrap after printing 
	}
		return 0;