why is my program skipping scanf()? [closed] - c

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Part of my assignment is to get user input; then, if the input is incorrect, prompt them to try again. When I use if statements and while loops in this way, they completely skip over the scanf command, and the program either runs infinitely or terminates immediately, skipping over the second chance for user input. Any idea how to fix this?
#include <stdio.h>
int main(void)
{
int number;
printf("please insert positive number\n");
scanf(" %d", &number);
// if the user inputs a value that is not a positive integer, it becomes false
// i want the if statement to re-prompt them to input the correct value
if (number <= 0)
{
printf("try again\n");
scanf(" %d", &number);
}
return 0;
}

Answer 1

scanf Returns the number of fields successfully converted and assigned; the return value does not include fields that were read but not assigned. A return value of 0 indicates that no fields were assigned.
The scanf function reads data from the standard input stream stdin and writes the data into the location given by argument. Each argument must be a pointer to a variable of a type that corresponds to a type specifier in format.
I recommend handle errors . it will happen in Real World code. (write Concise and robust Code).
so i recommend something like this:
#include <stdio.h>
int read_positive_int(int *n){
int retry = 3;
do{
printf("Please enter a positive number:\n");
if (scanf("%d", n) == 1){
if (*n > 0) return 1; //ok
}
} while (--retry);
return 0; //error
}
int main(void)
{
int n;
if (read_positive_int(&n))
printf("n = %d\n", n);
else
printf("error\n");
}
i hope this helps.

Answer 2

the code does what it's written to do, so in your case it's following:
message to user: enter a positive number
scanf: reads user's input
determine, if the number is positive
if yes - the if body will not be executed
and program ends
if not - print a message, read a number and program ends
the thing you are looking for is a loop
you want to do something like this:
while the entered number is not positive, ask the user to enter the number again
that's what loops are used for
int number;
printf("please insert positive number\n");
scanf("%d", &number);
while (number <= 0) {
printf("try again\n");
scanf("%d", &number);
}
return 0;