How to remove all characters in a string except alphabet?

Question

Given a string and a positive integer d. Some characters may be repeated in the given string. Rearrange characters of the given string such that the same characters become d distance away from each other. Note that there can be many possible rearrangements, the output should be one of the possible rearrangements.

example:
Input:  "abb", d = 2
Output: "bab"

Answer 1

#include<stdio.h>
int main(){
    char line[150];
    int i,j;
    printf("Enter a string: ");
    gets(line);
    for(i=0; line[i]!='\0'; ++i)
    {
        while (!((line[i]>='a'&&line[i]<='z') || (line[i]>='A'&&line[i]<='Z' || line[i]=='\0')))
        {
            for(j=i;line[j]!='\0';++j)
            {
                line[j]=line[j+1];
            }
            line[j]='\0';
        }
    }
    printf("Output String: ");
    puts(line);
    return 0;
}

Output:

Enter a string: p2'r"o@gram84iz./
Output String: programiz

Comments

Correct me if i am wrong, but don't you think in for loop instead of ++i/++j it should be i++/j++?

Answer 2

#include<stdio.h>
#include<stdlib.h>
void main(){
    char line[150];
    clrscr();
    int i,j;
    printf("Enter a string: ");
    gets(line);
    for(i=0; line[i]!='\0'; ++i)
    {
        while (!((line[i]>='a'&&line[i]<='z') || (line[i]>='A'&&line[i]<='Z' || line[i]=='\0')))
        {
            for(j=i;line[j]!='\0';++j)
            {
                line[j]=line[j+1];
            }
            line[j]='\0';
        }
    }
    printf("Output String: ");
    puts(line);
    getch();
}