Is there any function in C to replace getch() for my given program as it a non-standard function?

Question

I want and searching for a function or an alternative that could replace the non-standard getch() function of C language. I want help if any any function which can replace the getch() function from the code below or an appropriate alternative.

I am doing this since my college has asked me not to use the conio.h header file in my C programs.

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>

int main()
{
    int i=0, j=0, memAlloc=1;
    char *p, *q, a;
    p=(char *)calloc(1, sizeof(char));
    while(1)
    {
        a=getch();                   //getch() function 
        if(a!='\b'&&a!='\r')
        {
            p[i]=a;
            ++i;
            printf("%c", a);
            memAlloc++;
            p=realloc(p, memAlloc*sizeof(char));
        }
        if(a=='\b'&&i>=1)
        {
            printf("\b \b");
            --i;
        }
        if(a=='\r')
        {
            p[i]='\0';
            break;
        }
    }
    printf("\n");
    for (i=0; p[i]!='\0'; i++)
        printf("%c", p[i]);

    //Storing a string of only alphabets into a new dynamic array   
    q=(char *)calloc(1, sizeof(char));
    memAlloc=1;
    for (i=0; p[i]!='\0'; i++)
    {
        if (isalpha(p[I]))               //Checking for alphabet
            if(isupper(p[i]))
            {
                q[j]=p[i]+32;            //If uppercase alphabet convert it to lowercase
                memAlloc++;
                q=realloc(q, memAlloc*sizeof(char));
                j++;
            }
            else
            {
                q[j]=p[i];
                memAlloc++;
                q=realloc(q, memAlloc*sizeof(char));
                j++;    
            }           
    }
    q[j]='\0';                                         //Adding a null character to the end of the string
    free(p);
    printf("\n");
    for (i=0; q[i]!='\0'; i++)
        printf("%c", q[i]);

}

Here is the explanation of the program.

The program will take a string input from the user of unknown size and save it to the dynamic array. The user will keep on entering characters in a single line until he presses the enter key after which the whole string is saved to a dynamic array. The program then removes every character except alphabets and converting uppercase alphabets to it's lowercase and then saves the updated string to an another dynamic array.

Answer 1

try this scanf(" %c",&a);

also you can use getchar() but note that both of these functions(scanf and getchar()) will leave a \n in buffer and so in your next enter to loop , they will take that as input ,which means you can use two getchar() , or add a space in scanf like above.

as I see your code , you only want one character and no white-spaces which means you use scanf like above and that white space will be ignored.

Answer 2

If you can live with that the function will wait until it finds a newline or other whitespace character in stdin - the user needs to input more characters such as the newline made by the press to Return/ Enter - (contrary to the getch() function which does not wait for further input) you can use scanf() or getchar() (both header stdio.h) to get a single character from stdin:

a = getchar();

or

scanf("%c",&a);

Note, that in the case of getchar(), a shall be of type int instead of type char to catch the potential EOF which is returned by an error.

---

If you´re looking for a standard library function which does not wait for another character in stdin (unless it hasn´t encountered EOF) like getch(), the simple answer is:

There is no one. There are platform-dependent solutions only, like getch() for Windows and DOS is, but not a general standard one for all environments.

Answer 3

You can also use system command to control the terminal in linux like this:

char getch() {
        char c;

        system("stty raw -echo");
        c = getchar();
        system("stty -raw echo");

        return c;
}

This function does not require the user to press enter and takes input from the user without echoing. It requires you to add stdlib.h library to your code

Note: This function is only applicable to UNIX-based OS