scanf is not waiting for an integer input [duplicate] - c

Question

This question already has answers here:
Validate the type of input in a do-while loop
(5 answers)
While-loop ignores scanf the second time
(3 answers)
Closed 4 years ago.
printf("Enter an integer: ");
status = scanf("%d", &integer);
if (status == 0){
do{
printf("Please enter an integer: ");
status = scanf("%d", &integer);
}
while (status == 0);
}
I'm trying to prevent a user from entering a data of type of character. However, after the prompt, "Please enter an integer: ", it doesn't wait for an input. Hence, it goes into an infinite loop whenever I enter a letter at the first prompt. How do I fix this? Any heeelp will be greatly appreciated!

Answer 1

You need clean the buffer first, you can use fflush(stdin); like this:
int integer, status=0;
if (status == 0)
{
do
{
printf("\nPlease enter an integer: ");
status = scanf("%d", &integer);
fflush(stdin);
}
while (status == 0);
}
It's not in standard C using fflush(stdin) but you can clean the buffer in other ways.
You can build your own function to clean the buffer, like this:
void flushKeyBoard()
{
int ch; //variable to read data into
while((ch = getc(stdin)) != EOF && ch != '\n');
}
To clean the screen call this function:
void clrscr()
{
system("#cls||clear");
}
Final code:
#include <stdio.h>
void clrscr()
{
system("#cls||clear");
}
void flushKeyBoard()
{
int ch; //variable to read data into
while((ch = getc(stdin)) != EOF && ch != '\n');
}
int main()
{
int integer, status=0;
if (status == 0)
{
do
{
printf("\nPlease enter an integer: ");
status = scanf("%d", &integer);
flushKeyBoard();
clrscr();
}
while (status==0);
}
}

Answer 2

your %integer, should be declared int.
Like that:
int integer;
printf("Please input an integer value: ");
scanf("%d", &integer);