using malloc for char variable can not take input data character - c

Question

I am trying to implement DMA for char variable. But I am unable to take input. I tried with all the possible cases I know:
//gets(ptr_name);
//scanf("%[^\n]", &ptr_name);
//fgets(ptr_name, name, stdin);
But I can't even enter input data for the character variable ptr_name. I want to take input as "string with space" as input value. How to solve this problem?
And then how to print the entered name in the screen?
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
int main()
{
char* ptr_name;
int name, i;
printf("Enter number of characters for Name: ");
scanf("%d",&name);
ptr_name = (char*)malloc(name);
printf("Enter name: ");
//gets(ptr_name);
//scanf("%[^\n]", &ptr_name);
//fgets(ptr_name, name, stdin);
printf("\n Your name is: ");
puts(ptr_name);
free(ptr_name);
return 0;
}

Answer 1

scanf("%d", ...) does not consume the enter so the next scanf() gets an empty string.
you can use getchar() to consume the enter.
Also, you need to allocate additional byte for the zero at the end of the string / string terminator. See the + 1 in malloc().
As for your questions, your commented scanf() had & before argument 2 which isn't expected (char ** vs. char *) but other than that it will allow spaces in strings. puts() will print the entered name, alternatively you can modify the above printf() to print the name, e.g: printf("\n Your name is: %s", ptr_name);
Lastly, please consult Specifying the maximum string length to scanf dynamically in C (like "%*s" in printf) for dynamically limiting the input size, avoiding buffer overflow.
DISCLAIMER: The following is only "make it work" version of the program above and is not intended for real life use without appropriately checking return codes and limiting the input size:
#include <stdio.h>
#include <stdlib.h>
int main()
{
char* ptr_name;
int name, i;
printf("Enter number of characters for Name: ");
scanf("%d",&name);
getchar();
ptr_name = (char*)malloc(name + 1);
printf("Enter name: ");
scanf("%[^\n]", ptr_name);
printf("\n Your name is: ");
puts(ptr_name);
free(ptr_name);
return 0;
}

Answer 2

if you want to get input with spaces you need to use getline():
getline(&buffer,&size,stdin);
here an example:
#include <stdio.h>
#include <stdlib.h>
int main()
{
char* ptr_name;
int len;
printf("Enter number of characters for Name: ");
scanf("%d",&len);
ptr_name = (char*)malloc(len);
printf("Enter name: ");
getline(&ptr_name, &len, stdin);
printf("\n Your name is: %s", ptr_name);
free(ptr_name);
return 0;
}