What is wrong in the code?

Question

There is a problem with your keyboard: it randomly writes symbols when you are typing a text. You need to clean up the text by removing all symbols.

Task:
Take a text that includes some random symbols and translate it into a text that has none of them. The resulting text should only include letters and numbers.

Input Format:
A string with random symbols.

Output Format:
A string of the text with all the symbols removed.

Sample Input:
#l$e%ts go @an#d@@ g***et #l#unch$$

Sample Output:
lets go and get lunch

My code
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
int main() {
char str[50];
int i=0,f=0;
fgets(str,50,stdin);

while(str[i]!='\0')
{
if(isalpha(str[i])||isspace(str[i]))
{
printf("%c",str[i]);
}
i++;
}
return 0;
}

One of the test case fails

Answer 1

You have forgotten the numbers.

Answer 2

and you might need to consider more than 50 characters.

Answer 3

Lisa any suggestions on how to set the memory according to user input?

Answer 4

Have you tried something like
int n;
scanf("%d", &n);
So to first ask for how many characters will follow and then initialize the array accordingly?

might also want to try getline()
https://c-for-dummies.com/blog/?p=1112

Answer 5

Lisa thank you so much for all the answers and suggestions 😊