Question

I am trying to write a function for a bigger project that consists of working with character arrays. The current function I am working on, is supposed to save only alphabetical characters and remove any special characters (Ex: ! # @ $ ? ) and spaces. My current function works, but for some reason when I run it, the first character of the array is always removed. Why is that and how can I make it to save the first character instead?

#include <stdio.h>

int main(void)
{
  char phrase[101];

  printf("Enter a phrase to change:");
  fgets(phrase, 101, stdin);

  printf("original phrase: %s", phrase);

  int i = 0, j = 0;
  while(phrase[i] != '\0')
  {
    if( ('A' <= phrase[i] && phrase[i] >= 'Z') || 
        ('a' <= phrase[i] && phrase[i] >= 'z') )
    {
       phrase[j] = phrase[i];
       i++;
       j++;
    }
    else
      i++;

    phrase[j] = '\0';
  }

  printf("new phrase: %s\n", phrase);

  return 0;
}

Answer 1

The direction of your comparison operators is wrong. Instead of:

if( ('A' <= phrase[i] && phrase[i] >= 'Z') || 
    ('a' <= phrase[i] && phrase[i] >= 'z') )

You need:

if( ('A' <= phrase[i] && phrase[i] <= 'Z') || 
    ('a' <= phrase[i] && phrase[i] <= 'z') )

The way you wrote it will skip uppercase letters, which is probably why it skipped the first character of your input.

You should also move the line phrase[j] = '\0'; to after the loop, because otherwise you may overwrite the next character to be read.