#include <iostream>
 
using namespace std;
 
int main()
{
	int x = 0;
	do {
		cout << "Enter a number (-1 = quit): ";
		if(!(cin >> x)) {
			cout << "Please enter numeric characters only." << endl;
			cin.clear();
			cin.ignore(10000,'\n');
		}
		else if(x != -1) {
			cout << "You entered " << x << endl; // or goto any line of the code that u want //
		}
	}
	while(x != -1);
	cout << "Quitting program." << endl;
 
	return 0;
}

Name: S_INPUT.C
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
 
#define CR 0x0d     //carriage return
#define LF 0x0a     //Line feed
#define BACKSPACE 0x08
#define NULL 0      //Empty character
#define TRUE 1
#define FALSE 0
 
void input(char *string, int length);
 
 
void main()
{
    char string[6];
    long value;
 
    printf("Enter a 5-digit value: ");
    input(string,5);
    value = atol(string);
    printf("\nYou entered %ld\n",value);
}
 
/* The customized input() routine */
 
void input(char *string, int length)
{
    int done = FALSE;
    int index = 0;
    char ch;
 
    string[0] = NULL;   // init the buffer
 
    do
    {
        ch = getch();
 
/* Check to see if the buffer is full */
 
        if (index == length)
        {
            switch(ch)
            {
                case CR:
                    break;
                case BACKSPACE:
                    break;
                default:
                    ch = NULL;
                    break;
            }
        }
 
/* process the keyboard input */
 
        switch(ch)
        {
            case CR:        //Enter key
                putchar(ch);
                putchar(LF);
                string[index] = NULL;
                done = TRUE;
                break;
            case BACKSPACE:
                if(index==0)
                {
                    break;
                }
                else
                {
                    putchar(ch);
                    putchar(' ');
                    putchar(ch);
                    index--;
                    break;
                }
            case NULL:
                break;
            case '0':
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9':
                putchar(ch);
                string[index] = ch;
                index++;
                break;
            default:
                break;
        }
    }
    while(!done);
}

        putchar(ch);
        string[index] = ch;
        index++;
        break;