This first block of code was originally taken right here from the forum.
Code:
#include <stdio.h>
     
int main(void)
{
    int rows, columns, x, y;
 
    while(1)
    {
        printf("Enter number of rows: ");
        scanf("%d", &rows);
        if ((rows < 3) || (rows > 20))
            continue;
        printf("Enter number of columns: ");
            scanf("%d", &columns);
        if ((columns < 3) || (columns > 20))
            continue;
        break;
    }
    for (x = 0; x < rows; x++) 
    { 
        for (y = 0; y < columns; y++) 
        {
            if (x == 0 || x == rows - 1)            
            {
                if (y == 0)  
                printf("+");
                if (y == columns - 1)
                printf("+\n");
                else
                printf("-");
            }
        
            else
            {
                if (y == 0)  
                printf("|");
                if (y == columns - 1)
                printf("|\n");
                else
                printf(" ");
            }   
        }
    }    
return 0;
}
For my need I said thus:
Code:
#include <stdio.h>
#include <stdlib.h>
    
int main(void)
{
    int largura, altura, x, y;
    //system("cls");
    while(1)
    {
        printf("Digite a medida da largura: ");
            scanf("%d", &largura);
        if ((largura < 3) || (largura > 100))
            continue;
        printf("Digite a medida da altura: ");
        scanf("%d", &altura);
        if ((altura < 3) || (altura > 100))
            continue;
	break;
    }


    for (x = 0; x < altura; x++) 
    { 
        for (y = 0; y < largura; y++) 
        {
            if (x == 0 || x == altura - 1)            
            {
                if (y == 0)  
                //printf("+");
		printf("%c", 218);


		/*if (x != 0)  
                //printf("+");
		printf("a");*/


                if (y == largura - 1)
                //printf("+\n");
		printf("%c\n", 191);
                else
                //printf("-");
		printf("%c", 196);
           }
        
            else
            {
                if (y == 0)  
                //printf("|");
		printf("%c", 179);
                if (y == largura - 1)
                //printf("|\n");
		printf("%c\n", 179);
                else
                printf(" ");
            }   
        }
    }    
getchar();
return 0;
}
And I'm not getting the right characters on these two nodes as marked inside the white frames at the top of the print

Create a rectangle with ASCII code.-rect_error-jpg

Finally, I need to leave the rectangle completely closed as it should be, can any of your colleagues please help?
Thank you and God Bless ...