LCD prints the character twice?

Question

I have this problem with my 8051 project. I want to enter numbers and operation with keypad and print them in 16x2 LCD and the result using 8051 microcontroller. Everything works fine, I can do basic operations and see the results. But when I'm pressing characters from keypad, LCD prints the character twice. I couldn't see where the problem is. I'd be very glad if you help me. Thank you.

#include <reg51.h>

void lcdcmd(unsigned char);
void lcddata(unsigned char);
void MSDelay(unsigned int);
void disp_num(float num);
int get_num(char ch);
void lcdinit();
char scan_key(void);

sfr ldata = 0xA0;
sbit rs = P3^7;
sbit rw = P3^5;
sbit en = P3^6;
sbit r0=P1^0;
sbit r1=P1^1;
sbit r2=P1^2;
sbit r3=P1^3;
sbit c0=P1^4;
sbit c1=P1^5;
sbit c2=P1^6;
sbit c3=P1^7;

void lcdinit(){
    MSDelay(15000);
    lcdcmd(0x30);
    MSDelay(4500);
    lcdcmd(0x30);
    MSDelay(300);
    lcdcmd(0x30);
    MSDelay(600);
    lcdcmd(0x38);
    lcdcmd(0x0F);
    lcdcmd(0x01);
    lcdcmd(0x06);
    lcdcmd(0x80);
}

int main (void)
{
    while(1){
        unsigned int k=0, m=0, n=0;
        int k2, k1;
        char key, key1;
        unsigned char ch2,ch3;

        lcdinit();

        key = scan_key();
        k2 = get_num(key); // sayiya cevirdik. 
        lcddata(key); // lcd de goruntule. 

        ch2 = scan_key();
        lcddata(ch2);

        key1 = scan_key();
        k1 = get_num(key1);
        lcddata(key1);

        ch3 = scan_key();
        lcddata(ch3);
        lcdcmd(0x01);

        switch(ch2)
        {
        case 'A':
            disp_num(k1 + k2);
            break;

        case 'B':
            disp_num(k2 - k1);
            break;

        case 'C':
            disp_num(k2 * k1);
            break;

        case 'D':
            disp_num(k2 / k1);
            break;
        }
        return 0;
    }
}

void lcdcmd(unsigned char value)
{
    ldata = value;      
    rs = 0;
    rw = 0;
    en = 1;            
    MSDelay(50);
    en = 0;
    MSDelay(50);
}

void lcddata(unsigned char value)
{
    ldata = value;  
    rs = 1;
    rw = 0;
    en = 1;          
    MSDelay(50);
    en = 0;
    MSDelay(50);
}

void MSDelay(unsigned int itime)
{
    unsigned int i, j;

    for(i = 0;i < itime; i++)           
        for(j = 0; j < 5; j++);       
}

char scan_key()
{
    unsigned char c;
    c='s';
    while(!(c=='0' && c=='1' && c=='2' && c=='3' && c=='4'
                   && c=='5' && c=='6' && c=='7' && c=='8'
                   && c=='9' && c=='+' && c=='-' && c=='#'
                   && c=='$' && c=='*' && c=='/' ))
    {
      r0 = 0; r1 = 1; r2 = 1; r3 = 1;

      if(c0==0 && r0==0){ lcddata('7'); MSDelay(100000); return c = '7';}
      if(c1==0 && r0==0){ lcddata('8'); MSDelay(100000); return c = '8';}
      if(c2==0 && r0==0){ lcddata('9'); MSDelay(100000); return c = '9';}
      if(c3==0 && r0==0){ lcddata('A'); MSDelay(100000); return c = 'A';}

      r0 = 1; r1 = 0; r2 = 1; r3 = 1;

      if(c0==0 && r1==0){ lcddata('4'); MSDelay(100000); return c= '4';}
      if(c1==0 && r1==0){ lcddata('5'); MSDelay(100000); return c= '5';}
      if(c2==0 && r1==0){ lcddata('6'); MSDelay(100000); return c= '6';}
      if(c3==0 && r1==0){ lcddata('B'); MSDelay(100000); return c= 'B';}

      r0 = 1; r1 = 1; r2 = 0; r3 = 1;

      if(c0==0 && r2==0){ lcddata('1');MSDelay(100000); return c= '1';}
      if(c1==0 && r2==0){ lcddata('2');MSDelay(100000); return c= '2';}
      if(c2==0 && r2==0){ lcddata('3');MSDelay(100000); return c= '3';}
      if(c3==0 && r2==0){ lcddata('C');MSDelay(100000); return c= 'C';}

      r0 = 1; r1 = 1; r2 = 1; r3 = 0;

      if(c0==0 && r3==0){ lcddata('*');MSDelay(100000);return c= '*';}
      if(c1==0 && r3==0){ lcddata('0');MSDelay(100000);return c= '0';}
      if(c2==0 && r3==0){ lcddata('#');MSDelay(100000);return c= '#';}
      if(c3==0 && r3==0){ lcddata('D');MSDelay(100000);return c= 'D';}
    }
    return 0;
}

int get_num(char ch)         //convert char into int
{
    switch(ch)
    {
    case '0': return 0; break;
    case '1': return 1; break;
    case '2': return 2; break;
    case '3': return 3; break;
    case '4': return 4; break;
    case '5': return 5; break;
    case '6': return 6; break;
    case '7': return 7; break;
    case '8': return 8; break;
    case '9': return 9; break;
    }
    return 0;
}

void disp_num(float num)            //displays number on LCD
{
    unsigned char UnitDigit  = 0;  //It will contain unit digit of numb
    unsigned char TenthDigit = 0;  //It will contain 10th position digit of numb
    unsigned char decimal = 0;
    int j;
    int numb;
    j=(int)(num*10);
    numb=(int)num;

    TenthDigit = (numb/10);          // Findout Tenth Digit

    if( TenthDigit != 0)             // If it is zero, then don't display
      lcddata(TenthDigit+0x30);  // Make Char of TenthDigit and then display it on LCD

    UnitDigit = numb - TenthDigit*10;

    lcddata(UnitDigit+0x30);     // Make Char of UnitDigit and then display it on LCD
    MSDelay(2000000);
}

Answer 1

I solved the probem by removing lcddata() functions from here:

key = scan_key();
    k2 = get_num(key); // sayiya cevirdik. 
    lcddata(key); // lcd de goruntule. 

    ch2 = scan_key();
    lcddata(ch2);

    key1 = scan_key();
    k1 = get_num(key1);
    lcddata(key1);

    ch3 = scan_key();
    lcddata(ch3);
    lcdcmd(0x01);

I didn't understand what you were trying to say about while() in scan_key() function, it works fine in the simulation. But now I want to create a 20 seconds delay for the result in this operation, I tried it with MSDelay() function but nothing changed.

Edit: sorry guys, now I realized the mistake in the while(). That was a huge mistake, I'll fix that and thank you all.